isort: format codebase

Change-Id: I6f11d123b68fd077f558d3c21349c55c5f251019
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/383715
Reviewed-by: Gavin Mak <gavinmak@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Mike Frysinger <vapier@google.com>

tests/test_error.py

@@ -18,13 +18,14 @@ import inspect
 import pickle
 import unittest
 
-import error
-import project
-import git_command
-import fetch
 import command
+import error
+import fetch
+import git_command
+import project
 from subcmds import all_modules
 
+
 imports = all_modules + [
     error,
     project,