Revert recent "git merge <msg> HEAD <commit>..." deprecation

This reverts commit c0ecb07 "git-pull.sh:
Fix call to git-merge for new command format" and

commit b81e00a "git-merge: a deprecation
notice of the ancient command line syntax".

They caused a "git pull" (without any arguments, and without any local
commits---only to update to the other side) to warn that commit log
message is ignored because the merge resulted in a fast-forward.

Another possible solution is to add an extra option to "git merge" so that
"git pull" can tell it that the message given is not coming from the end
user (the canned message is passed just in case the merge resulted in a
non-ff and caused commit), but I think it is easier _not_ to deprecate the
old syntax.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-merge.c

@@ -796,11 +796,6 @@ static int suggest_conflicts(void)
 	return 1;
 }
 
-static const char deprecation_warning[] =
-	"'git merge <msg> HEAD <commit>' is deprecated. Please update\n"
-	"your script to use 'git merge -m <msg> <commit>' instead.\n"
-	"In future versions of git, this syntax will be removed.";
-
 static struct commit *is_old_style_invocation(int argc, const char **argv)
 {
 	struct commit *second_token = NULL;
@@ -814,7 +809,6 @@ static struct commit *is_old_style_invocation(int argc, const char **argv)
 			die("'%s' is not a commit", argv[1]);
 		if (hashcmp(second_token->object.sha1, head))
 			return NULL;
-		warning(deprecation_warning);
 	}
 	return second_token;
 }

git-pull.sh

@@ -216,7 +216,7 @@ fi
 
 merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
 test true = "$rebase" &&
-	exec git rebase $diffstat $strategy_args --onto $merge_head \
+	exec git-rebase $diffstat $strategy_args --onto $merge_head \
 	${oldremoteref:-$merge_head}
-exec git merge $verbosity $diffstat $no_commit $squash $no_ff $ff_only $log_arg $strategy_args \
-	-m "$merge_name" $merge_head
+exec git-merge $diffstat $no_commit $squash $no_ff $ff_only $log_arg $strategy_args \
+	"$merge_name" HEAD $merge_head $verbosity