This patch also replaces "editor = False" by "editor =
cmdutil.getcommiteditor()", because:
- it allows to hook commit message determination easily, even in the
case without "--edit"
- it avoids regression (or additional care) around saving
"last-message.txt", even if MQ's "newcommit()" changes its
implementation logic from "localrepository.commit" to
"localrepository.commitctx" with "memctx" in the future
to save commit message into "last-messge.txt" with "memctx",
"editor" should be valid function.
Before this patch, "hg qrefresh" and "hg qfold" invoke "ui.edit()"
explicitly to get commit message edited manually.
This requires explicit "localrepository.savecommitmessage()"
invocation to save edited commit message into ".hg/last-message.txt",
because unexpected exception raising may abort command execution
before saving it in "localrepository.commit()".
This patch uses "editor" argument of "localrepository.commit()"
instead of explicit "ui.edit()" invocation for "hg qnew" and "hg qfold"
"localrepository.commit()" will invoke "desceditor()" function newly
added by this patch, and save edited commit message into
".hg/last-message.txt" automatically.
This patch passes not "editor" but "desceditor" to "commit()", because
"hg qnew" and "hg qfold" require editor function to return edited
message (and invoke "patchheader.setmessage()" with it) if not empty,
or default message otherwise.
This patch also avoids "not q.applied" check at "hg qrefresh --edit",
because it is also checked in "queue.refresh()", and it is not needed
to get commit message from patch header before "queue.refresh()".
