## Description The `mr checkout --set-upstream-to` flag codepath has no test coverage. This was identified during review of !1832. ## Expected behavior Add a test case in `internal/commands/mr/checkout/mr_checkout_test.go` that exercises the `--set-upstream-to` flag, verifying that `git branch --set-upstream-to <upstream>` is called with the correct arguments. ## References - Identified in !1832 by @theoretick: https://gitlab.com/gitlab-org/cli/-/merge_requests/1832#note_3270717606