Add cygwin check after initialization. Resolves #437

tests/main_test.py

@@ -7,6 +7,7 @@ import mock
 import pytest
 
 from pre_commit import main
+from pre_commit.error_handler import PreCommitSystemExit
 from pre_commit.util import cwd
 from testing.auto_namedtuple import auto_namedtuple
 
@@ -142,3 +143,16 @@ def test_help_cmd_in_empty_directory(
         mock.call(['help', 'run']),
         mock.call(['run', '--help']),
     ])
+
+
+def test_expected_fatal_error_no_git_repo(
+        tempdir_factory, cap_out, mock_out_store_directory,
+):
+    with cwd(tempdir_factory.get()):
+        with pytest.raises(PreCommitSystemExit):
+            main.main([])
+    assert cap_out.get() == (
+        'An error has occurred: FatalError: git failed. '
+        'Is it installed, and are you in a Git repository directory?\n'
+        'Check the log at ~/.pre-commit/pre-commit.log\n'
+    )