ci/check-cherry-picks: fail without proper cherry-pick

.github/workflows/check-cherry-picks.yml

@@ -20,12 +20,12 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           fetch-depth: 0
-          filter: blob:none
+          filter: tree:0
           path: trusted
 
       - name: Check cherry-picks
         env:
           BASE_SHA: ${{ github.event.pull_request.base.sha }}
           HEAD_SHA: ${{ github.event.pull_request.head.sha }}
         run: |
-          ./trusted/maintainers/scripts/check-cherry-picks.sh "$BASE_SHA" "$HEAD_SHA"
+          ./trusted/ci/check-cherry-picks.sh "$BASE_SHA" "$HEAD_SHA"

maintainers/scripts/check-cherry-picks.sh → ci/check-cherry-picks.sh

@@ -11,14 +11,15 @@ fi
 # Make sure we are inside the nixpkgs repo, even when called from outside
 cd "$(dirname "${BASH_SOURCE[0]}")"
 
-PICKABLE_BRANCHES=${PICKABLE_BRANCHES:-master staging release-??.?? staging-??.??}
+PICKABLE_BRANCHES="master release-??.?? staging-??.?? haskell-updates python-updates"
 problem=0
 
-commits="$(git rev-list \
-  -E -i --grep="cherry.*[0-9a-f]{40}" --reverse \
-  "$1..$2")"
+# Not everyone calls their remote "origin"
+remote="$(git remote -v | grep -i 'NixOS/nixpkgs' | head -n1 | cut -f1 || true)"
 
-while read new_commit_sha ; do
+commits="$(git rev-list --reverse "$1..$2")"
+
+while read -r new_commit_sha ; do
   if [ -z "$new_commit_sha" ] ; then
     continue  # skip empty lines
   fi
@@ -33,30 +34,47 @@ while read new_commit_sha ; do
   original_commit_sha=$(
     git rev-list --max-count=1 --format=format:%B "$new_commit_sha" \
     | grep -Ei -m1 "cherry.*[0-9a-f]{40}" \
-    | grep -Eoi -m1 '[0-9a-f]{40}'
+    | grep -Eoi -m1 '[0-9a-f]{40}' || true
   )
-  if [ "$?" != "0" ] ; then
-    echo "  ? Couldn't locate original commit hash in message"
-    [ "$GITHUB_ACTIONS" = 'true' ] && echo ::endgroup::
+  if [ -z "$original_commit_sha" ] ; then
+    if [ "$GITHUB_ACTIONS" = 'true' ] ; then
+      echo ::endgroup::
+      echo -n "::error ::"
+    else
+      echo -n "  ✘ "
+    fi
+    echo "Couldn't locate original commit hash in message"
+    echo "Note this should not necessarily be treated as a hard fail, but a reviewer's attention should" \
+      "be drawn to it and github actions have no way of doing that but to raise a 'failure'"
+    problem=1
     continue
   fi
 
   set -f # prevent pathname expansion of patterns
-  for branch_pattern in $PICKABLE_BRANCHES ; do
+  for pattern in $PICKABLE_BRANCHES ; do
     set +f # re-enable pathname expansion
 
+    # Reverse sorting by refname and taking one match only means we can only backport
+    # from unstable and the latest stable. That makes sense, because even right after
+    # branch-off, when we have two supported stable branches, we only ever want to cherry-pick
+    # **to** the older one, but never **from** it.
+    # This makes the job significantly faster in the case when commits can't be found,
+    # because it doesn't need to iterate through 20+ branches, which all need to be fetched.
+    branches="$(git for-each-ref --sort=-refname --format="%(refname)" \
+      "refs/remotes/${remote:-origin}/$pattern" | head -n1)"
+
     while read -r picked_branch ; do
       if git merge-base --is-ancestor "$original_commit_sha" "$picked_branch" ; then
         echo "  ✔ $original_commit_sha present in branch $picked_branch"
 
-        range_diff_common='git range-diff
+        range_diff_common='git --no-pager range-diff
           --no-notes
           --creation-factor=100
           '"$original_commit_sha~..$original_commit_sha"'
           '"$new_commit_sha~..$new_commit_sha"'
         '
 
-        if $range_diff_common --no-color | grep -E '^ {4}[+-]{2}' > /dev/null ; then
+        if $range_diff_common --no-color 2> /dev/null | grep -E '^ {4}[+-]{2}' > /dev/null ; then
           if [ "$GITHUB_ACTIONS" = 'true' ] ; then
             echo ::endgroup::
             echo -n "::warning ::"
@@ -79,11 +97,7 @@ while read new_commit_sha ; do
         # move on to next commit
         continue 3
       fi
-    done <<< "$(
-      git for-each-ref \
-      --format="%(refname)" \
-      "refs/remotes/origin/$branch_pattern"
-    )"
+    done <<< "$branches"
   done
 
   if [ "$GITHUB_ACTIONS" = 'true' ] ; then