I looked through git history and we already had a commit trying to fix this; we regressed because there's no test. I'd like a test added that invokes gh pr status in a no-branch situation to cover this case moving forward.

I think I've addressed this concern to a degree.

• update the "blank context" mock to return an ErrNotOnAnyBranch if no branch has been set.
• add a test to pr_test.go that checks that the command runs to completion if there is no branch.

I don't think this is completely foolproof, since it relies on the mock's behavior staying synchronized with the regular filesystem context, so I'm not 100% happy with it.

But I didn't see any existing tests that set up a real Git repository (on a real filesystem, using real git), and I'm assuming that you don't want to add that with this change.

I was imagining using our CmdStubber's StubError to have the git branch call result in the expected error. Sorry for the back and forth but I'd rather see that approach (unless there's a reason why it wouldn't work that I'm forgetting about).