fusion: flake8 fixes

Author: FabioLuporini

pyop2/fusion/extended.py

@@ -35,7 +35,6 @@
 derived from ``base.py``."""
 
 import sys
-import os
 import ctypes
 from copy import deepcopy as dcopy
 from itertools import groupby

pyop2/fusion/interface.py

@@ -35,7 +35,6 @@
 itself, whereas others directly from application code."""
 
 import os
-import sys
 from contextlib import contextmanager
 from decorator import decorator