test_url_generation_with_proxy: do not use contextlib.nested()

This method does not exist in Python 3, use the "@mock.patch.object" decorator
instead.

Change-Id: Ic45fea1553320c61be284a9397b54fd32f7d30ef
Fix a typo in a comment in v2 client

Change-Id: I835af00af62046e9a391a08e675bc6eeb7267824
Merge "Fix a typo in a comment in v2 client"