test: Try harder to locate caucase.sh .

caucase/test.py

@@ -3138,9 +3138,9 @@ if getattr(CaucaseTest, 'assertItemsEqual', None) is None: # pragma: no cover
   CaucaseTest.assertItemsEqual = CaucaseTest.assertCountEqual
 # pylint: enable=no-member
 
-_caucase_root = os.path.normpath(
-  os.path.join(os.path.dirname(__file__), os.path.pardir),
-)
+_caucase_root = os.path.dirname(__file__)
+while not os.path.exists(os.path.join(_caucase_root, '.git')):
+  _caucase_root = os.path.normpath(os.path.join(_caucase_root, os.path.pardir))
 _caucase_sh_path = find_executable(
   'caucase.sh',
   path=os.path.join(
@@ -3158,7 +3158,6 @@ def _runCaucaseSh(*args):
       close_fds=True,
       env={
         'CAUCASE_PYTHON': sys.executable,
-        'PYTHONPATH': _caucase_root,
       },
     )
     stdout, _ = process.communicate()