GitLab

* lisp/vc/log-edit.el (log-edit-set-header): Extract from
`log-edit-toggle-header'.
(log-edit-extract-headers): Separate the summary, when extracted
from header, from the rest of the message with an empty line.

* lisp/vc/vc-git.el (vc-git-log-edit-toggle-amend): Move the summary
line, if present, to the Summary header.