Fix tests (#1133)

* Fix traitlets warning

* Fix failing pytest

Author: fcollonval

jupyterlab_git/__init__.py

@@ -31,7 +31,7 @@ class JupyterLabGit(Configurable):
     actions = Dict(
         help="Actions to be taken after a git command. Each action takes a list of commands to execute (strings). Supported actions: post_init",
         config=True,
-        trait=List(
+        value_trait=List(
             trait=Unicode(), help='List of commands to run. E.g. ["touch baz.py"]'
         )
         # TODO Validate

jupyterlab_git/git.py

@@ -1350,8 +1350,9 @@ async def get_content(self, contents_manager, filename, path):
             )
         except tornado.web.HTTPError as error:
             # Handle versioned file being deleted case
-            if error.status_code == 404 and error.log_message.startswith(
-                "No such file or directory: "
+            if error.status_code == 404 and (
+                error.log_message.startswith("No such file or directory: ")
+                or error.log_message.startswith("file or directory does not exist:")
             ):
                 return ""
             raise error

setup.cfg

@@ -27,6 +27,7 @@ install_requires =
   nbformat
   packaging
   pexpect
+  traitlets~=5.0
 include_package_data = True
 zip_safe = False
 python_requires = >=3.6,<4