Merge branch 'hn/checkout-m-autostash-refine' into jch

The autostash fallback in 'git checkout -m' has been refined to only retry when there are local changes. Additionally, a blank line now visually separates autostash conflict advice from the subsequent branch-switch message. * hn/checkout-m-autostash-refine: checkout -m: refine autostash fallback sequencer: teach autostash apply to report conflicts