Make pep8 happy (except for regex in tar_scm:299)

Addressing the feedback of pep8 tool. The regex in line 299 will stay as
it is due to readability.

Signed-off-by: Jan Blunck <jblunck@infradead.org>
Address some feedback from pylint

Signed-off-by: Jan Blunck <jblunck@infradead.org>