Added a bot-generated PR-comment with a simple status table

The littlefs CI is actually in a nice state that generates a lot of
information about PRs (code/stack/struct changes, line/branch coverage
changes, benchmark changes), but GitHub's UI has changed overtime to
make CI statuses harder to find for some reason.

This bot comment should hopefully make this information easy to find
without creating too much noise in the discussion. If not, this can
always be changed later.

.github/workflows/release.yml

@@ -5,6 +5,10 @@ on:
     branches: [master]
     types: [completed]
 
+defaults:
+  run:
+    shell: bash -euv -o pipefail {0}
+
 jobs:
   release:
     runs-on: ubuntu-22.04
@@ -82,14 +86,14 @@ jobs:
           echo "LFS_PREV_VERSION=$LFS_PREV_VERSION" >> $GITHUB_ENV
 
       # try to find results from tests
-      - name: collect-table
+      - name: create-table
         run: |
           # previous results to compare against?
           [ -n "$LFS_PREV_VERSION" ] && curl -sS \
-            "$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/`
-              `status/$LFS_PREV_VERSION?per_page=100" \
+            "$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/status/$LFS_PREV_VERSION`
+              `?per_page=100" \
             | jq -re 'select(.sha != env.GITHUB_SHA) | .statuses[]' \
-            >> prev-statuses.json \
+            >> prev-status.json \
             || true
 
           # build table for GitHub
@@ -113,7 +117,7 @@ jobs:
                 export PREV="$(jq -re '
                     select(.context == "'"sizes (thumb${c:+, $c}) / $s"'").description
                     | capture("(?<prev>[0-9∞]+)").prev' \
-                  prev-statuses.json || echo 0)"
+                  prev-status.json || echo 0)"
                 ./scripts/summary.py $f --max=stack_limit -Y \
                   | awk '
                     NR==2 {$1=0; printf "%s B",$NF}
@@ -138,11 +142,12 @@ jobs:
             [ -e $f ] && table[$i,$j]=$( \
               export PREV="$(jq -re '
                   select(.context == "'"cov / $s"'").description
-                  | capture("(?<prev>[0-9\\.]+)").prev' \
-                prev-statuses.json || echo 0)"
+                  | capture("(?<prev_a>[0-9]+)/(?<prev_b>[0-9]+)")
+                  | 100*((.prev_a|tonumber) / (.prev_b|tonumber))' \
+                prev-status.json || echo 0)"
               ./scripts/cov.py -u $f -f$s -Y \
                 | awk -F '[ /%]+' -v s=$s '
-                  NR==2 {$1=0; printf "%.1f%% of %d %s",$4,$3,s}
+                  NR==2 {$1=0; printf "%d/%d %s",$2,$3,s}
                   NR==2 && ENVIRON["PREV"]+0 != 0 {
                     printf " (%+.1f%%)",$4-ENVIRON["PREV"]
                   }' \
@@ -163,7 +168,7 @@ jobs:
               export PREV="$(jq -re '
                   select(.context == "'"bench / $s"'").description
                   | capture("(?<prev>[0-9]+)").prev' \
-                prev-statuses.json || echo 0)"
+                prev-status.json || echo 0)"
               ./scripts/summary.py $f -f$s=bench_$s -Y \
                 | awk '
                   NR==2 {$1=0; printf "%s B",$NF}
@@ -184,7 +189,7 @@ jobs:
             do
               echo -n " " >> table.txt
               [[ i -eq 2 && j -eq 5 ]] && echo -n "**Benchmarks**" >> table.txt
-              echo -n "${table[$i,$j]}" >> table.txt
+              echo -n "${table[$i,$j]:-}" >> table.txt
               echo -n " |" >> table.txt
             done
             echo >> table.txt
@@ -193,7 +198,7 @@ jobs:
           cat table.txt
 
       # find changes from history
-      - name: collect-changes
+      - name: create-changes
         run: |
           [ -n "$LFS_PREV_VERSION" ] || exit 0
           # use explicit link to github commit so that release notes can
@@ -235,15 +240,18 @@ jobs:
         run: |
           # create release and patch version tag (vN.N.N)
           # only draft if not a patch release
-          [ -e table.txt ] && export TABLES="$(cat table.txt)"
-          [ -e changes.txt ] && export CHANGES="$(cat changes.txt)"
+          [ -e table.txt ] && cat table.txt >> release.txt
+          echo >> release.txt
+          [ -e changes.txt ] && cat changes.txt >> release.txt
+          cat release.txt
+
           curl -sS -X POST -H "authorization: token ${{secrets.BOT_TOKEN}}" \
             "$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/releases" \
-            -d "$(jq -n '{
+            -d "$(jq -n --rawfile release release.txt '{
               tag_name: env.LFS_VERSION,
               name: env.LFS_VERSION | rtrimstr(".0"),
               target_commitish: "${{github.event.workflow_run.head_sha}}",
               draft: env.LFS_VERSION | endswith(".0"),
-              body: [env.TABLES, env.CHANGES | select(.)] | join("\n\n")
+              body: $release,
             }' | tee /dev/stderr)"