Fixed issue where a invaild path cant be found and gitlab api returns a

400 status code.

pyup/providers/gitlab.py

@@ -77,7 +77,7 @@ def get_file(self, repo, path, branch):
         try:
             contentfile = repo.files.get(file_path=path, ref=branch)
         except GitlabGetError as e:
-            if e.response_code == 404:
+            if e.response_code in [404, 400]:
                 logger.warning("Unable to get {path}".format(
                     path=path,
                 ))