We had some change in source code (glance.py) to make os-xenapi
be compitable with both py2 and py3. But the modules in the UT
have not been changed accordingly. So some mocks on module's
method don't take effective.
This commit is to fix the failures in test_glance.
Change-Id: I42cbe4f5dc5cec5d28394b9502196ff9c9bb8761
Closes-Bug: 1757928