Fix #322 by only removing git environment variables while cloning

pre_commit/main.py

@@ -22,16 +22,6 @@ from pre_commit.runner import Runner
 # to install packages to the wrong place.  We don't want anything to deal with
 # pyvenv
 os.environ.pop('__PYVENV_LAUNCHER__', None)
-# https://github.com/pre-commit/pre-commit/issues/300
-# In git 2.6.3 (maybe others), git exports this while running pre-commit hooks
-os.environ.pop('GIT_WORK_TREE', None)
-# In git 1.9.1 (maybe others), git exports these while running pre-commit hooks
-# in submodules.  In the general case this causes problems.
-# These are covered by test_install_in_submodule_and_run
-# Causes git clone to clone wrong thing
-os.environ.pop('GIT_DIR', None)
-# Causes 'error invalid object ...' during commit
-os.environ.pop('GIT_INDEX_FILE', None)
 
 
 def main(argv=None):

pre_commit/store.py

@@ -14,6 +14,7 @@ from pre_commit.prefixed_command_runner import PrefixedCommandRunner
 from pre_commit.util import clean_path_on_failure
 from pre_commit.util import cmd_output
 from pre_commit.util import cwd
+from pre_commit.util import no_git_env
 
 
 logger = logging.getLogger('pre_commit')
@@ -114,9 +115,11 @@ class Store(object):
 
         dir = tempfile.mkdtemp(prefix='repo', dir=self.directory)
         with clean_path_on_failure(dir):
-            cmd_output('git', 'clone', '--no-checkout', url, dir)
+            cmd_output(
+                'git', 'clone', '--no-checkout', url, dir, env=no_git_env(),
+            )
             with cwd(dir):
-                cmd_output('git', 'reset', sha, '--hard')
+                cmd_output('git', 'reset', sha, '--hard', env=no_git_env())
 
         # Update our db with the created repo
         with sqlite3.connect(self.db_path) as db:

pre_commit/util.py

@@ -71,6 +71,20 @@ def shell_escape(arg):
     return "'" + arg.replace("'", "'\"'\"'".strip()) + "'"
 
 
+def no_git_env():
+    # Too many bugs dealing with environment variables and GIT:
+    # https://github.com/pre-commit/pre-commit/issues/300
+    # In git 2.6.3 (maybe others), git exports GIT_WORK_TREE while running
+    # pre-commit hooks
+    # In git 1.9.1 (maybe others), git exports GIT_DIR and GIT_INDEX_FILE
+    # while running pre-commit hooks in submodules.
+    # GIT_DIR: Causes git clone to clone wrong thing
+    # GIT_INDEX_FILE: Causes 'error invalid object ...' during commit
+    return dict(
+        (k, v) for k, v in os.environ.items() if not k.startswith('GIT_')
+    )
+
+
 @contextlib.contextmanager
 def tarfile_open(*args, **kwargs):
     """Compatibility layer because python2.6"""