Adding upstream version 2.21.0.

Signed-off-by: Daniel Baumann <daniel@debian.org>

pre_commit/commands/run.py

@@ -263,7 +263,7 @@ def _all_filenames(args: argparse.Namespace) -> Collection[str]:
 
 def _get_diff() -> bytes:
     _, out, _ = cmd_output_b(
-        'git', 'diff', '--no-ext-diff', '--ignore-submodules', retcode=None,
+        'git', 'diff', '--no-ext-diff', '--ignore-submodules', check=False,
     )
     return out
 
@@ -318,7 +318,7 @@ def _has_unmerged_paths() -> bool:
 def _has_unstaged_config(config_file: str) -> bool:
     retcode, _, _ = cmd_output_b(
         'git', 'diff', '--no-ext-diff', '--exit-code', config_file,
-        retcode=None,
+        check=False,
     )
     # be explicit, other git errors don't mean it has an unstaged config.
     return retcode == 1
@@ -333,7 +333,7 @@ def run(
     stash = not args.all_files and not args.files
 
     # Check if we have unresolved merge conflict files and fail fast.
-    if _has_unmerged_paths():
+    if stash and _has_unmerged_paths():
         logger.error('Unmerged files.  Resolve before committing.')
         return 1
     if bool(args.from_ref) != bool(args.to_ref):
@@ -420,7 +420,11 @@ def run(
             return 1
 
         skips = _get_skips(environ)
-        to_install = [hook for hook in hooks if hook.id not in skips]
+        to_install = [
+            hook
+            for hook in hooks
+            if hook.id not in skips and hook.alias not in skips
+        ]
         install_hook_envs(to_install, store)
 
         return _run_hooks(config, hooks, skips, args)