Do not rely on hash ordering in tests

With tox 1.7.2 hash randomization will be on by default, causing
random failures of our tests. How to reproduce:
* Update tox
* Run something like:
  $ for i in {1..20}; do tox -epy27 || break; done

Change-Id: I52c10c47a7a1c0e6a9e436efb090bbcb0fb02edc
Closes-bug: #1348818
Merge "Do not rely on hash ordering in tests"