make-test: Python pep8 compliance for sequences

make-test: Python pep8 compliance for sequences

For sequences, (strings, lists, tuples), use the fact that
empty sequences are false. A tiny change towards getting
full pep8 compliance, which will look good.
Yes: if not seq:
     if seq:
No:  if len(seq):
     if not len(seq):
(https://www.python.org/dev/peps/pep-0008/)

Change-Id: I6b565bef424f81afc66aba3b0041a5029a9f8954
Signed-off-by: Naveen Joy <najoy@cisco.com>