pep8: Fix E301 pep8 violations.

Fix "E301: expected (1 or 2) blank line" pep8 violations.

integrations/perforce/git_p4.py

@@ -39,9 +39,11 @@ except ImportError:
         """This exception is raised when a process run by check_call() returns
         a non-zero exit status.  The exit status will be stored in the
         returncode attribute."""
+
         def __init__(self, returncode, cmd):
             self.returncode = returncode
             self.cmd = cmd
+
         def __str__(self):
             return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)