Fix bug in QueryTest#test_inner_outer.
Fix bug in QueryTest#test_inner_outer.

Test failed when same Image used in multiple Observations.

JoeCohen/mushroom-observer,raysuelzer/mushroom-observer,JoeCohen/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,JoeCohen/mushroom-observer,JoeCohen/mushroom-observer,MushroomObserver/mushroom-observer,JoeCohen/mushroom-observer,raysuelzer/mushroom-observer,MushroomObserver/mushroom-observer,raysuelzer/mushroom-observer,raysuelzer/mushroom-observer,pellaea/mushroom-observer,JoeCohen/mushroom-observer,JoeCohen/mushroom-observer,raysuelzer/mushroom-observer,pellaea/mushroom-observer,MushroomObserver/mushroom-observer,raysuelzer/mushroom-observer,MushroomObserver/mushroom-observer,raysuelzer/mushroom-observer