Update pre-submit to run against renamed "main" branch. (#1330)

Author: cnauroth

cloudbuild/README.md

@@ -1,7 +1,7 @@
 # Continuous Integration via Cloud Build
 
 [Cloud Build](https://cloud.google.com/cloud-build/) is configured to trigger on
-`/gcbrun` comment from maintainer in PR to the `master` branch.
+`/gcbrun` comment from maintainer in PR to the `main` branch.
 
 Cloud Build triggers a set of build steps, configured in a `cloudbuild.yaml`
 config file. These steps are:

cloudbuild/presubmit.sh

@@ -24,8 +24,8 @@ configure_gcloud_ssh_key() {
   chmod 600 "${HOME}/.ssh/google_compute_engine"
 }
 
-# Fetches master branch from GitHub and "resets" local changes to be relative to it,
-# so we can diff what changed relatively to master branch.
+# Fetches main branch from GitHub and "resets" local changes to be relative to it,
+# so we can diff what changed relatively to main branch.
 initialize_git_repo() {
   rm -fr .git
   git config --global init.defaultBranch main
@@ -35,21 +35,21 @@ initialize_git_repo() {
   git config user.name "ia-tests"
 
   git remote add origin "https://github.com/GoogleCloudDataproc/initialization-actions.git"
-  git fetch origin master
+  git fetch origin main
   # Fetch all PRs to get history for PRs created from forked repos
   git fetch origin +refs/pull/*/merge:refs/remotes/origin/pr/* > /dev/null 2>&1
 
   git reset --hard "${COMMIT_SHA}"
 
-  git rebase origin/master
+  git rebase origin/main
 }
 
-# This function adds all changed files to git "index" and diffs them against master branch
+# This function adds all changed files to git "index" and diffs them against main branch
 # to determine all changed files and looks for tests in directories with changed files.
 determine_tests_to_run() {
   # Infer the files that changed
-  mapfile -t DELETED_BUILD_FILES < <(git diff origin/master --name-only --diff-filter=D | grep BUILD)
-  mapfile -t CHANGED_FILES < <(git diff origin/master --name-only)
+  mapfile -t DELETED_BUILD_FILES < <(git diff origin/main --name-only --diff-filter=D | grep BUILD)
+  mapfile -t CHANGED_FILES < <(git diff origin/main --name-only)
   echo "Deleted BUILD files: ${DELETED_BUILD_FILES[*]}"
   echo "Changed files: ${CHANGED_FILES[*]}"