Release scripts: add a git note with the cherrypick origin

If the patch-id differ because of merge conflict or subtle adjacent
change, the cherrypick origin was missing, resulting in non existent
cherrypick lines in the changelog.

If the cherrypicks are done by the script, adds the cherrypick origin
to a git note and use that origin when generating the release note. Also
fallback to the commit hash of the resulting commit if the cherrypick
origin cannot be found.

Fixes #2272.

--
Change-Id: I311bbe777ea82be05f9fba0a658bab075ed1bd97
Reviewed-on: https://cr.bazel.build/8042
PiperOrigin-RevId: 144075867
MOS_MIGRATED_REVID=144075867

1 files changed, 32 insertions, 4 deletions

diff --git a/scripts/release/common.sh b/scripts/release/common.sh
index 33b2c38440..5f83af7d1c 100755
--- a/scripts/release/common.sh
+++ b/scripts/release/common.sh
@@ -140,6 +140,25 @@ function get_release_baseline() {
   git merge-base $(get_master_ref) "${1:-HEAD}"
 }
 
+# Returns the list of (commit hash, patch-id) from $1..$2
+# Args:
+#   $1: the first commit in the list (excluded)
+#   $2: the last commit in the list
+function get_patch_ids() {
+  git_log_hash "$1" "$2" | xargs git show | git patch-id
+}
+
+# Returns the original commit a commit was cherry-picked from master
+# Args:
+#   $1: the commit to find
+#   $2: the baseline from which to look for (up to master)
+#   $3: master ref (optional, default master)
+#   $4: The list of master changes as returned by get_patch_ids (optional)
+function get_cherrypick_origin() {
+  local master=${3:-$(get_master_ref)}
+  local master_changes="${4-$(get_patch_ids "${2}" "${master}")}"
+}
+
 # Get the list of cherry-picks since master
 # Args:
 #   $1: branch, default to HEAD
@@ -154,10 +173,19 @@ function get_cherrypicks() {
   local master_changes="$(git_log_hash "${baseline}" "${master}" | xargs git show | git patch-id)"
   # Now for each changes on the release branch
   for i in ${changes}; do
-    # Find the change with the same patch-id on the master branch
-    echo "${master_changes}" \
-      | grep "^$(git show "$i" | git patch-id | cut -d " " -f 1)" \
-      | cut -d " " -f 2
+    local hash=$(git notes --ref=cherrypick show "$i" 2>/dev/null || true)
+    if [ -z "${hash}" ]; then
+      # Find the change with the same patch-id on the master branch if the note is not present
+      hash=$(echo "${master_changes}" \
+          | grep "^$(git show "$i" | git patch-id | cut -d " " -f 1)" \
+          | cut -d " " -f 2)
+    fi
+    if [ -z "${hash}" ]; then
+     # We don't know which cherry-pick it is coming from, fall back to the new commit hash.
+     echo "$i"
+    else
+     echo "${hash}"
+    fi
   done
 }