deprecate python_venv language

pre_commit/commands/migrate_config.py

@@ -42,6 +42,14 @@ def _migrate_sha_to_rev(contents: str) -> str:
     return re.sub(r'(\n\s+)sha:', r'\1rev:', contents)
 
 
+def _migrate_python_venv(contents: str) -> str:
+    return re.sub(
+        r'(\n\s+)language: python_venv\b',
+        r'\1language: python',
+        contents,
+    )
+
+
 def migrate_config(config_file: str, quiet: bool = False) -> int:
     with open(config_file) as f:
         orig_contents = contents = f.read()
@@ -55,6 +63,7 @@ def migrate_config(config_file: str, quiet: bool = False) -> int:
 
     contents = _migrate_map(contents)
     contents = _migrate_sha_to_rev(contents)
+    contents = _migrate_python_venv(contents)
 
     if contents != orig_contents:
         with open(config_file, 'w') as f:

pre_commit/repository.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 import json
 import logging
 import os
+import shlex
 from typing import Any
 from typing import Sequence
 
@@ -68,6 +69,14 @@ def _hook_install(hook: Hook) -> None:
     logger.info('Once installed this environment will be reused.')
     logger.info('This may take a few minutes...')
 
+    if hook.language == 'python_venv':
+        logger.warning(
+            f'`repo: {hook.src}` uses deprecated `language: python_venv`.  '
+            f'This is an alias for `language: python`.  '
+            f'Often `pre-commit autoupdate --repo {shlex.quote(hook.src)}` '
+            f'will fix this.',
+        )
+
     lang = languages[hook.language]
     assert lang.ENVIRONMENT_DIR is not None