merge script: handle --no-ff --no-commit correctly

In a --no-ff merge with conflicts, "git commit" used to forget the
--no-ff when used to complete the merge.  That was fixed by
v1.6.1-rc1~134^2 (builtin-commit: use reduce_heads() only when
appropriate, 2008-10-03) for the builtin merge.  Port the change to
the merge script in contrib/examples.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/examples/git-merge.sh

@@ -52,7 +52,7 @@ squash= no_commit= log_arg=
 
 dropsave() {
 	rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
-		 "$GIT_DIR/MERGE_STASH" || exit 1
+		 "$GIT_DIR/MERGE_STASH" "$GIT_DIR/MERGE_MODE" || exit 1
 }
 
 savestate() {
@@ -585,7 +585,15 @@ else
 	do
 		echo $remote
 	done >"$GIT_DIR/MERGE_HEAD"
-	printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG"
+	printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG" ||
+		die "Could not write to $GIT_DIR/MERGE_MSG"
+	if test "$allow_fast_forward" != t
+	then
+		printf "%s" no-ff
+	else
+		:
+	fi >"$GIT_DIR/MERGE_MODE" ||
+		die "Could not write to $GIT_DIR/MERGE_MODE"
 fi
 
 if test "$merge_was_ok" = t