Merge branch 'rr/rebase-checkout-reflog'

Invocations of "git checkout" used internally by "git rebase" were
counted as "checkout", and affected later "git checkout -" to the
the user to an unexpected place.

* rr/rebase-checkout-reflog:
checkout: respect GIT_REFLOG_ACTION
status: do not depend on rebase reflog messages
t/t2021-checkout-last: "checkout -" should work after a rebase finishes
wt-status: remove unused field in grab_1st_switch_cbdata
t7512: test "detached from" as well

diff --cc builtin/checkout.c
Simple merge

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

diff --cc wt-status.c
Simple merge