This adjusts the logic for determining whether to skip some tests when not in the primary branch, and allows for running these tests locally.
Follow-up to [47000], [47001], [49264], [49267], [49280].
See #50401.
git-svn-id: https://develop.svn.wordpress.org/trunk@49916 602fd350-edb4-49c9-b593-d223f7449a82