diff --git a/scripts/dbgbmap.py b/scripts/dbgbmap.py
index ef829a8e..2c0a6ea4 100755
--- a/scripts/dbgbmap.py
+++ b/scripts/dbgbmap.py
@@ -1203,7 +1203,9 @@ class Btree:
             if path:
                 yield (bid-rid + (rbyd.weight-1), rbyd,
                         # path tail is usually redundant unless corrupt
-                        path_[:-1] if rbyd else path_)
+                        path_[:-1]
+                            if path_ and path_[-1][1] == rbyd
+                            else path_)
             else:
                 yield bid-rid + (rbyd.weight-1), rbyd
             bid += rbyd.weight - rid + 1
@@ -1754,8 +1756,6 @@ class Mtree:
             # iterate over mrootchain
             path_ = []
             for mroot in self.mrootchain:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     if path:
@@ -1763,6 +1763,9 @@ class Mtree:
                     else:
                         return mroot
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # no mtree? must be inlined in mroot
         if self.mtree is None:
             if mid.mbid >= (1 << self.mbits):
@@ -1903,12 +1906,13 @@ class Mtree:
                 yield mroot
 
             if path or depth:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     return
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # do we even have an mtree?
         if self.mtree is not None:
             # include the mtree root even if the weight is zero
@@ -1945,7 +1949,11 @@ class Mtree:
                     if path:
                         yield ((bid-rid + (rbyd.weight-1), rbyd),
                                 # path tail is usually redundant unless corrupt
-                                path_[:-1] if rbyd else path_)
+                                path_[:-1]
+                                    if path_
+                                        and isinstance(path_[-1][1], Rbyd)
+                                        and path_[-1][1] == rbyd
+                                    else path_)
                     else:
                         yield (bid-rid + (rbyd.weight-1), rbyd)
                     mid = self.mid(bid-rid + (rbyd.weight-1) + 1)
@@ -2128,8 +2136,6 @@ class Mtree:
             # iterate over mrootchain
             path_ = []
             for mroot in self.mrootchain:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     if path:
@@ -2137,6 +2143,9 @@ class Mtree:
                     else:
                         return mroot
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # no mtree? must be inlined in mroot
         if self.mtree is None:
             mdir = Mdir(0, self.mroot)
@@ -3423,7 +3432,9 @@ class Lfs:
                     if path:
                         yield (pos, rbyd,
                                 # path tail is usually redundant unless corrupt
-                                path_[:-1] if rbyd else path_)
+                                path_[:-1]
+                                    if path_ and path_[-1][1] == rbyd
+                                    else path_)
                     else:
                         yield pos, rbyd
                     pos += rbyd.weight
diff --git a/scripts/dbgbmapd3.py b/scripts/dbgbmapd3.py
index 63e89acb..714c1bf0 100755
--- a/scripts/dbgbmapd3.py
+++ b/scripts/dbgbmapd3.py
@@ -1233,7 +1233,9 @@ class Btree:
             if path:
                 yield (bid-rid + (rbyd.weight-1), rbyd,
                         # path tail is usually redundant unless corrupt
-                        path_[:-1] if rbyd else path_)
+                        path_[:-1]
+                            if path_ and path_[-1][1] == rbyd
+                            else path_)
             else:
                 yield bid-rid + (rbyd.weight-1), rbyd
             bid += rbyd.weight - rid + 1
@@ -1784,8 +1786,6 @@ class Mtree:
             # iterate over mrootchain
             path_ = []
             for mroot in self.mrootchain:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     if path:
@@ -1793,6 +1793,9 @@ class Mtree:
                     else:
                         return mroot
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # no mtree? must be inlined in mroot
         if self.mtree is None:
             if mid.mbid >= (1 << self.mbits):
@@ -1933,12 +1936,13 @@ class Mtree:
                 yield mroot
 
             if path or depth:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     return
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # do we even have an mtree?
         if self.mtree is not None:
             # include the mtree root even if the weight is zero
@@ -1975,7 +1979,11 @@ class Mtree:
                     if path:
                         yield ((bid-rid + (rbyd.weight-1), rbyd),
                                 # path tail is usually redundant unless corrupt
-                                path_[:-1] if rbyd else path_)
+                                path_[:-1]
+                                    if path_
+                                        and isinstance(path_[-1][1], Rbyd)
+                                        and path_[-1][1] == rbyd
+                                    else path_)
                     else:
                         yield (bid-rid + (rbyd.weight-1), rbyd)
                     mid = self.mid(bid-rid + (rbyd.weight-1) + 1)
@@ -2158,8 +2166,6 @@ class Mtree:
             # iterate over mrootchain
             path_ = []
             for mroot in self.mrootchain:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     if path:
@@ -2167,6 +2173,9 @@ class Mtree:
                     else:
                         return mroot
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # no mtree? must be inlined in mroot
         if self.mtree is None:
             mdir = Mdir(0, self.mroot)
@@ -3453,7 +3462,9 @@ class Lfs:
                     if path:
                         yield (pos, rbyd,
                                 # path tail is usually redundant unless corrupt
-                                path_[:-1] if rbyd else path_)
+                                path_[:-1]
+                                    if path_ and path_[-1][1] == rbyd
+                                    else path_)
                     else:
                         yield pos, rbyd
                     pos += rbyd.weight
diff --git a/scripts/dbgbtree.py b/scripts/dbgbtree.py
index 22d2bd3d..1692c6a4 100755
--- a/scripts/dbgbtree.py
+++ b/scripts/dbgbtree.py
@@ -1111,7 +1111,9 @@ class Btree:
             if path:
                 yield (bid-rid + (rbyd.weight-1), rbyd,
                         # path tail is usually redundant unless corrupt
-                        path_[:-1] if rbyd else path_)
+                        path_[:-1]
+                            if path_ and path_[-1][1] == rbyd
+                            else path_)
             else:
                 yield bid-rid + (rbyd.weight-1), rbyd
             bid += rbyd.weight - rid + 1
@@ -1352,6 +1354,12 @@ class TreeArt:
     def __iter__(self):
         return iter(self.tree)
 
+    def __bool__(self):
+        return bool(self.tree)
+
+    def __len__(self):
+        return len(self.tree)
+
     # render an rbyd rbyd tree for debugging
     @classmethod
     def _fromrbydrtree(cls, rbyd, **args):
diff --git a/scripts/dbglfs.py b/scripts/dbglfs.py
index 0c5308a2..557eaedb 100755
--- a/scripts/dbglfs.py
+++ b/scripts/dbglfs.py
@@ -1160,7 +1160,9 @@ class Btree:
             if path:
                 yield (bid-rid + (rbyd.weight-1), rbyd,
                         # path tail is usually redundant unless corrupt
-                        path_[:-1] if rbyd else path_)
+                        path_[:-1]
+                            if path_ and path_[-1][1] == rbyd
+                            else path_)
             else:
                 yield bid-rid + (rbyd.weight-1), rbyd
             bid += rbyd.weight - rid + 1
@@ -1711,8 +1713,6 @@ class Mtree:
             # iterate over mrootchain
             path_ = []
             for mroot in self.mrootchain:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     if path:
@@ -1720,6 +1720,9 @@ class Mtree:
                     else:
                         return mroot
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # no mtree? must be inlined in mroot
         if self.mtree is None:
             if mid.mbid >= (1 << self.mbits):
@@ -1860,12 +1863,13 @@ class Mtree:
                 yield mroot
 
             if path or depth:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     return
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # do we even have an mtree?
         if self.mtree is not None:
             # include the mtree root even if the weight is zero
@@ -1902,7 +1906,11 @@ class Mtree:
                     if path:
                         yield ((bid-rid + (rbyd.weight-1), rbyd),
                                 # path tail is usually redundant unless corrupt
-                                path_[:-1] if rbyd else path_)
+                                path_[:-1]
+                                    if path_
+                                        and isinstance(path_[-1][1], Rbyd)
+                                        and path_[-1][1] == rbyd
+                                    else path_)
                     else:
                         yield (bid-rid + (rbyd.weight-1), rbyd)
                     mid = self.mid(bid-rid + (rbyd.weight-1) + 1)
@@ -2085,8 +2093,6 @@ class Mtree:
             # iterate over mrootchain
             path_ = []
             for mroot in self.mrootchain:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     if path:
@@ -2094,6 +2100,9 @@ class Mtree:
                     else:
                         return mroot
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # no mtree? must be inlined in mroot
         if self.mtree is None:
             mdir = Mdir(0, self.mroot)
@@ -3380,7 +3389,9 @@ class Lfs:
                     if path:
                         yield (pos, rbyd,
                                 # path tail is usually redundant unless corrupt
-                                path_[:-1] if rbyd else path_)
+                                path_[:-1]
+                                    if path_ and path_[-1][1] == rbyd
+                                    else path_)
                     else:
                         yield pos, rbyd
                     pos += rbyd.weight
@@ -3648,6 +3659,12 @@ class TreeArt:
     def __iter__(self):
         return iter(self.tree)
 
+    def __bool__(self):
+        return bool(self.tree)
+
+    def __len__(self):
+        return len(self.tree)
+
     # render an rbyd rbyd tree for debugging
     @classmethod
     def _fromrbydrtree(cls, rbyd, **args):
@@ -3808,7 +3825,7 @@ class TreeArt:
 
         return '%s ' % ''.join(trunk)
 
-    # some more renderers
+# some more renderers
 
 # render a btree rbyd tree for debugging
 @classmethod
diff --git a/scripts/dbgmtree.py b/scripts/dbgmtree.py
index 41182441..35f0e685 100755
--- a/scripts/dbgmtree.py
+++ b/scripts/dbgmtree.py
@@ -1126,7 +1126,9 @@ class Btree:
             if path:
                 yield (bid-rid + (rbyd.weight-1), rbyd,
                         # path tail is usually redundant unless corrupt
-                        path_[:-1] if rbyd else path_)
+                        path_[:-1]
+                            if path_ and path_[-1][1] == rbyd
+                            else path_)
             else:
                 yield bid-rid + (rbyd.weight-1), rbyd
             bid += rbyd.weight - rid + 1
@@ -1677,8 +1679,6 @@ class Mtree:
             # iterate over mrootchain
             path_ = []
             for mroot in self.mrootchain:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     if path:
@@ -1686,6 +1686,9 @@ class Mtree:
                     else:
                         return mroot
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # no mtree? must be inlined in mroot
         if self.mtree is None:
             if mid.mbid >= (1 << self.mbits):
@@ -1826,12 +1829,13 @@ class Mtree:
                 yield mroot
 
             if path or depth:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     return
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # do we even have an mtree?
         if self.mtree is not None:
             # include the mtree root even if the weight is zero
@@ -1868,7 +1872,11 @@ class Mtree:
                     if path:
                         yield ((bid-rid + (rbyd.weight-1), rbyd),
                                 # path tail is usually redundant unless corrupt
-                                path_[:-1] if rbyd else path_)
+                                path_[:-1]
+                                    if path_
+                                        and isinstance(path_[-1][1], Rbyd)
+                                        and path_[-1][1] == rbyd
+                                    else path_)
                     else:
                         yield (bid-rid + (rbyd.weight-1), rbyd)
                     mid = self.mid(bid-rid + (rbyd.weight-1) + 1)
@@ -2051,8 +2059,6 @@ class Mtree:
             # iterate over mrootchain
             path_ = []
             for mroot in self.mrootchain:
-                name = mroot.lookup(-1, TAG_MAGIC)
-                path_.append((mroot.mid, mroot, name))
                 # stop here?
                 if depth and len(path_) >= depth:
                     if path:
@@ -2060,6 +2066,9 @@ class Mtree:
                     else:
                         return mroot
 
+                name = mroot.lookup(-1, TAG_MAGIC)
+                path_.append((mroot.mid, mroot, name))
+
         # no mtree? must be inlined in mroot
         if self.mtree is None:
             mdir = Mdir(0, self.mroot)
@@ -2247,6 +2256,12 @@ class TreeArt:
     def __iter__(self):
         return iter(self.tree)
 
+    def __bool__(self):
+        return bool(self.tree)
+
+    def __len__(self):
+        return len(self.tree)
+
     # render an rbyd rbyd tree for debugging
     @classmethod
     def _fromrbydrtree(cls, rbyd, **args):
diff --git a/scripts/dbgrbyd.py b/scripts/dbgrbyd.py
index b5deafb4..439d43dc 100755
--- a/scripts/dbgrbyd.py
+++ b/scripts/dbgrbyd.py
@@ -1299,6 +1299,15 @@ class TreeArt:
         else:
             self.width = 0
 
+    def __iter__(self):
+        return iter(self.tree)
+
+    def __bool__(self):
+        return bool(self.tree)
+
+    def __len__(self):
+        return len(self.tree)
+
     # render an rbyd rbyd tree for debugging
     @classmethod
     def _fromrbydrtree(cls, rbyd, **args):