Bug 1378950 - Fix test_summary_performance_data non-determinism
Bug 1378950 - Fix test_summary_performance_data non-determinism

Previously it was dependant on the order of results returned by the
API, when the backing DB query doesn't use an ORDER BY. This means
that changes in the optimiser (eg upgrading to a different MySQL
version) could cause the test to fail.

edmorley/treeherder,tojon/treeherder,tojonmz/treeherder,tojon/treeherder,tojon/treeherder,KWierso/treeherder,tojonmz/treeherder,edmorley/treeherder,tojonmz/treeherder,KWierso/treeherder,tojonmz/treeherder,tojon/treeherder,tojonmz/treeherder,KWierso/treeherder,edmorley/treeherder,KWierso/treeherder,edmorley/treeherder,tojonmz/treeherder