Add parser arguments for prepare-commit-msg

pre_commit/main.py

@@ -107,6 +107,17 @@ def _add_run_options(parser: argparse.ArgumentParser) -> None:
         '--commit-msg-filename',
         help='Filename to check when running during `commit-msg`',
     )
+    parser.add_argument(
+        '--commit-msg',
+        help=(
+            'Type of commit string to pass though as ENV' +
+            'during `prepare-commit-msg`'
+        ),
+    )
+    parser.add_argument(
+        '--commit-sha',
+        help='Commit sha to pass though as ENV during `prepare-commit-msg`',
+    )
     parser.add_argument(
         '--remote-name', help='Remote name used by `git push`.',
     )