builtin/am: honor --signoff also when --rebasing

Signoff is handled in parse_mail(), but not in parse_mail_rebasing(),
since the latter is only used when git-rebase calls git-am with the
--rebasing option, and --signoff is never passed in this case.

In order to introduce (in the upcoming commits) support for
`git-rebase --signoff`, we must make git-am pay attention to it also
in the rebase case. This can be done by moving the conditional
addition of the signoff from parse_mail() to the caller am_run(),
after either of the parse_mail*() functions were called.

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: Oblomov

builtin/am.c

@@ -1321,9 +1321,6 @@ static int parse_mail(struct am_state *state, const char *mail)
 	strbuf_addbuf(&msg, &mi.log_message);
 	strbuf_stripspace(&msg, 0);
 
-	if (state->signoff)
-		am_signoff(&msg);
-
 	assert(!state->author_name);
 	state->author_name = strbuf_detach(&author_name, NULL);
 
@@ -1848,6 +1845,9 @@ static void am_run(struct am_state *state, int resume)
 			if (skip)
 				goto next; /* mail should be skipped */
 
+			if (state->signoff)
+				am_append_signoff(state);
+
 			write_author_script(state);
 			write_commit_msg(state);
 		}