Fix various whitespace issues reported by pyflakes

- E201 whitespace after '['
- E202 whitespace before '}'
- E221 multiple spaces before operator
- E222 multiple spaces after operator
- E225 missing whitespace around operator
- E226 missing whitespace around arithmetic operator
- E231 missing whitespace after ','
- E261 at least two spaces before inline comment
- E271 multiple spaces after keyword

Fixed automatically with autopep8:

  git ls-files | grep py$ | xargs autopep8 --in-place \
    --select E201,E202,E221,E222,E225,E226,E231,E261,E271

Change-Id: I367113eb8c847eb460532c7c2f8643f33040308c
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/254601
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: David Pursehouse <dpursehouse@collab.net>

gitc_utils.py

@@ -121,7 +121,7 @@ def generate_gitc_manifest(gitc_manifest, manifest, paths=None):
   index = 0
   while index < len(projects):
     _set_project_revisions(
-        projects[index:(index+NUM_BATCH_RETRIEVE_REVISIONID)])
+        projects[index:(index + NUM_BATCH_RETRIEVE_REVISIONID)])
     index += NUM_BATCH_RETRIEVE_REVISIONID
 
   if gitc_manifest is not None: