'pending' test result state should be at the highest priority at the revision level

Right now, when deriving the test result state of the revision from the all tests results, we do a max([t.state for t in test_results]). So if we have two test results, one 'pending' and the other 'success', we'll derive that the revision has the 'success' state.

It's misleading to do so. If we have a pending test, we should wait until it's finished to give more indication to the user (the revision level test result will be displayed in the list of series). In the case above, the revision test state should be 'pending', indicating that we are still waiting for a test to finish before we can conclude anything else.