Merge branch 'rj/status-bisect-while-rebase'

"git status" is taught to show both the branch being bisected and
being rebased when both are in effect at the same time.

* rj/status-bisect-while-rebase:
  status: fix branch shown when not only bisecting

diff --cc branch.c
Simple merge

diff --cc ref-filter.c
Simple merge

diff --cc t/t7512-status-help.sh
Simple merge

diff --cc worktree.c
Simple merge

diff --cc wt-status.c
Simple merge