Merge branch 'hn/git-checkout-m-with-stash'

"git checkout -m another-branch" was invented to deal with local changes to paths that are different between the current and the new branch, but it gave only one chance to resolve conflicts. The command was taught to create a stash to save the local changes. * hn/git-checkout-m-with-stash: checkout -m: autostash when switching branches checkout: rollback lock on early returns in merge_working_tree sequencer: teach autostash apply to take optional conflict marker labels sequencer: allow create_autostash to run silently stash: add --label-ours, --label-theirs, --label-base for apply