Fix blank line issues reported by flake8

- E301 expected 1 blank line
- E302 expected 2 blank lines
- E303 too many blank lines
- E305 expected 2 blank lines after class or function definition
- E306 expected 1 blank line before a nested definition

Fixed automatically with autopep8:

  git ls-files | grep py$ | xargs autopep8 --in-place \
    --select E301,E302,E303,E305,E306

Manually fix issues in project.py caused by misuse of block comments.

Change-Id: Iee840fcaff48aae504ddac9c3e76d2acd484f6a9
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/254599
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: David Pursehouse <dpursehouse@collab.net>

subcmds/forall.py

@@ -277,6 +277,7 @@ without iterating through the remaining projects.
         return
       yield [mirror, opt, cmd, shell, cnt, config, project]
 
+
 class WorkerKeyboardInterrupt(Exception):
   """ Keyboard interrupt exception for worker processes. """
   pass
@@ -285,6 +286,7 @@ class WorkerKeyboardInterrupt(Exception):
 def InitWorker():
   signal.signal(signal.SIGINT, signal.SIG_IGN)
 
+
 def DoWorkWrapper(args):
   """ A wrapper around the DoWork() method.
 
@@ -303,6 +305,7 @@ def DoWorkWrapper(args):
 
 def DoWork(project, mirror, opt, cmd, shell, cnt, config):
   env = os.environ.copy()
+
   def setenv(name, val):
     if val is None:
       val = ''