Use except x as y instead of except x, y

According to https://docs.python.org/3/howto/pyporting.html the
syntax changed in Python 3.x. The new syntax is usable with
Python >= 2.6 and should be preferred to be compatible with Python3.

Change-Id: I4624c9be5c70e4401c67f4f053daa9e85e3cdea4
Merge "Use except x as y instead of except x, y"