[ci] fix files_changed to differentiate when you are in a pr or main …

…as well as fix check_bazel and files_changed base_sha to point to HEAD~1 when running on a main merge

ci/check_bazel.sh

@@ -17,7 +17,7 @@ if [ -n "$GITHUB_BASE_REF" ]; then
   base_sha=$(git rev-parse "$GITHUB_BASE_REF")
 else
   echo "Not in a pull request, skipping base ref fetch."
-  base_sha=$(git rev-parse HEAD)
+  base_sha=$(git rev-parse HEAD~1)
 fi
 
 # Get the latest commit SHA for the PR branch (the head ref in the forked repository)

ci/files_changed.sh

@@ -5,16 +5,33 @@
 #
 # Usage: ./ci/files_changed.sh <regex>
 
-set -e
+set -euo pipefail
 
 # Trap to handle unexpected errors and log them
 trap 'echo "An unexpected error occurred during file change check."; echo "check_result=1" >> "$GITHUB_OUTPUT"; exit 1' ERR
 
-# Check for file changes
-if git rev-parse --abbrev-ref HEAD | grep -q ^main$ || git diff --name-only "origin/$GITHUB_BASE_REF" | grep -E "$1" ; then
+# Determine the base ref or fallback to HEAD~1 when running on main
+if [[ -z "${GITHUB_BASE_REF:-}" ]]; then
+  echo "GITHUB_BASE_REF is empty, likely running on main branch. Using HEAD~1 for comparison."
+  base_ref="HEAD~1"
+else
+  base_ref="origin/$GITHUB_BASE_REF"
+fi
+
+if git rev-parse --abbrev-ref HEAD | grep -q ^main$ ; then
+  echo "Relevant file changes detected!"
+  echo "check_result=0" >> "$GITHUB_OUTPUT"
+  exit 0
+fi
+
+# Run git diff and store output
+diff_output=$(git diff --name-only "$base_ref" || exit 1)  # Ensure git diff failures are caught
+
+# Check for relevant file changes
+if echo "$diff_output" | grep -E "$1" ; then
   echo "Relevant file changes detected!"
   echo "check_result=0" >> "$GITHUB_OUTPUT"
-  exit 0  # Relevant changes detected
+  exit 0
 else
   echo "No relevant changes found."
   echo "check_result=2" >> "$GITHUB_OUTPUT"