Merge branch 'nd/branch-show-rebase-bisect-state'

Add a bit more information to "git status" during a rebase/bisect
session.

* nd/branch-show-rebase-bisect-state:
status, branch: fix the misleading "bisecting" message
branch: show more information when HEAD is detached
status: show more info than "currently not on any branch"
wt-status: move wt_status_get_state() out to wt_status_print()
wt-status: split wt_status_state parsing function out
wt-status: move strbuf into read_and_strip_branch()

diff --cc builtin/branch.c
Simple merge

diff --cc t/t7406-submodule-update.sh
Simple merge

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

diff --cc wt-status.c
Simple merge

diff --cc wt-status.h
Simple merge