Work around the issue with random PYTHONHASHSEED

New tox and python3.3 set a random PYTHONHASHSEED value by default,
affecting the way keys of dicts and sets are ordered, which breaks
unit tests when dicts/sets are compared. Until those comparisons are
fixed, we can work around this so that unit tests would pass for
people, who use the latest tox version.

Related-Bug: #1348818

Change-Id: I910824bcc440c84b924d9a30c423d1a2b8318a61