PushImageTest is add a tag to an image. When looking at the images, it is comparing all of the decoration with the tag. This works fine as long as the image only has 1 tag, once it gets more, the lookup for the image starts to fail. The image is deleted later in the test, so if the image with the tag is not found, the delete wont happen and subsequent lookups will fail. This most likely wont happen if you run the complete suite because the suite is cleaning up, but it will happen if you run a single test.

Another problem is that PushImageTest wont wait until the freshly tagged image was successfully pushed.