fix(ci): infer branch name if only commit given

After migration of github, we only use the commit ID for the
pre-ci-check script. This is problematic, because it checks for merges,
excluding the integration branch (expected to have merges), based on the
branch _name_.

In this commit, if a full SHA is detected as the branch "name", use "git
branch --points-at" to get a branch name, then use that to exclude
integration branches (or not).  If no branch name is found, the branch
name "" is used, which will trigger the normal merge check (because ""
does not match the integration branch name).
Signed-off-by: Robert Schmidt <robert.schmidt@openairinterface.org>

ci-scripts/pre-ci-check.sh

@@ -55,8 +55,17 @@ done
 # ----------------------------
 # Merged commits
 # ----------------------------
-mergeCommits=$(git rev-list --merges --abbrev-commit "$TARGET_BRANCH".."$SOURCE_BRANCH")
-if [[ ! "$SOURCE_BRANCH" =~ ^(origin/)?integration_[0-9]{4}_w[0-9]{2}$ ]]; then
+if [[ "$SOURCE_BRANCH" =~ ^[0-9a-f]{40}$ ]]; then
+  # note: if no branch could be found, it will result in "" and git rev-list
+  # will use the commit ID. Exclude "HEAD detached at", then use first branch
+  # name.
+  BRANCH_NAME=$(git branch -a --points-at $SOURCE_BRANCH --format='%(refname:short)' | grep -v detached | head -n1)
+  echo "SHA recognized in $SOURCE_BRANCH, using \"$BRANCH_NAME\" as branch name"
+else
+  BRANCH_NAME="$SOURCE_BRANCH"
+fi
+if [[ ! "$BRANCH_NAME" =~ ^(origin/)?integration_[0-9]{4}_w[0-9]{2}$ ]]; then
+    mergeCommits=$(git rev-list --merges --abbrev-commit "$TARGET_BRANCH".."$SOURCE_BRANCH")
     if [[ -n "$mergeCommits" ]]; then
         message="Error: Following merge commits are found in the source branch history. Please rebase your branch.\n\n"
         message+="$(echo "$mergeCommits" | paste -sd ',' | sed 's/,/, /g')\n"