Merge branch 'js/rebase-i-clean-up-upon-continue-to-skip'

Abandoning an already applied change in "git rebase -i" with "--continue" left CHERRY_PICK_HEAD and confused later steps. * js/rebase-i-clean-up-upon-continue-to-skip: rebase -i: do not leave a CHERRY_PICK_HEAD file behind t3404: demonstrate CHERRY_PICK_HEAD bug