Fix failures introduced by the new version of mock

Fix failures introduced by the new version of mock

This reverts commit 1b60df85ba3ad442c2e4e7e52538e1b9a1bf9378.

The new version of mock is now released which has the fix to
make mock.patch.stopall behave deterministically. The code to
stop double-mocking is no longer required.

Other fixes:

'assert_has_calls' that have changed behavior in the new version
(no longer accepts single calls).

Calls to non-existent assert methods that did not exist and were
silently passing.

Use of autospec on a class with decorated functions.

Closes-Bug: #1473369
Change-Id: I164a9af2a7f9ac0f0229ec3c5071f7a470445c98