Remove unused import from test_nokey.py

test_nokey.py was recently merged into the source tree with an
unused import (copy.py).

Change-Id: I27b7040b5719ea21d1e0a79afe499bf7fa5a94e5
Fixes: Bug #1131275
Add pyflakes to test-requires

pyflakes needs to be installed in the venv

Change-Id: Ie7aada13da4e191108363c80daf719212d06d316
Fixes: Bug #1131275