ci: Fix get_changed_files_output (#5944)

* ci: Fix get_changed_files_output

* Update project_tests.yml

* ci: Fix presubmit checks

* ci: Use fetch-depth:0 instead of --unshallow

.github/workflows/infra_tests.yml

@@ -15,8 +15,9 @@ jobs:
           access_token: ${{ github.token }}
 
       - uses: actions/checkout@v2
-      - run: |  # Needed for git diff to work.
-          git fetch origin master --depth 1
+        with:  # Needed for git diff to work. (get_changed_files)
+          fetch-depth: 0
+      - run: |
           git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/master
 
       - name: Setup python environment

.github/workflows/presubmit.yml

@@ -16,8 +16,9 @@ jobs:
           access_token: ${{ github.token }}
 
       - uses: actions/checkout@v2
-      - run: |  # Needed for git diff to work.
-          git fetch origin master --depth 1
+        with:  # Needed for git diff to work. (get_changed_files)
+          fetch-depth: 0
+      - run: |
           git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/master
 
       - name: Setup python environment

.github/workflows/project_tests.yml

@@ -48,8 +48,9 @@ jobs:
           access_token: ${{ github.token }}
 
       - uses: actions/checkout@v2
-      - run: |  # Needed for git diff to work.
-          git fetch origin master --depth 1
+        with:  # Needed for git diff to work. (get_changed_files)
+          fetch-depth: 0
+      - run: |
           git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/master
 
       - name: Clear unnecessary files

infra/ci/build.py

@@ -38,7 +38,7 @@ LANGUAGES_WITH_COVERAGE_SUPPORT = ['c', 'c++', 'go', 'jvm', 'rust']
 def get_changed_files_output():
   """Returns the output of a git command that discovers changed files."""
   branch_commit_hash = subprocess.check_output(
-      ['git', 'merge-base', 'FETCH_HEAD', 'origin/HEAD']).strip().decode()
+      ['git', 'merge-base', 'HEAD', 'origin/HEAD']).strip().decode()
 
   return subprocess.check_output(
       ['git', 'diff', '--name-only', branch_commit_hash + '..']).decode()

infra/presubmit.py

@@ -346,7 +346,7 @@ def yapf(paths, validate=True):
 def get_changed_files():
   """Return a list of absolute paths of files changed in this git branch."""
   branch_commit_hash = subprocess.check_output(
-      ['git', 'merge-base', 'FETCH_HEAD', 'origin/HEAD']).strip().decode()
+      ['git', 'merge-base', 'HEAD', 'origin/HEAD']).strip().decode()
 
   diff_commands = [
       # Return list of modified files in the commits on this branch.