reset: make the reminder output consistent with "checkout"

git reset without argument displays a summary of the local modification,
like this:

    $ git reset
    Makefile: locally modified

Some people have problems with this; they look like an error message.

This patch makes its output mimic how "git checkout $another_branch"
reports the paths with local modifications.  "git add --refresh --verbose"
is changed in the same way.

It also adds a header to make it clear that the output is informative,
and not an error.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>

builtin-reset.c

@@ -108,7 +108,8 @@ static int update_index_refresh(int fd, struct lock_file *index_lock, int flags)
 	if (read_cache() < 0)
 		return error("Could not read index");
 
-	result = refresh_cache(flags) ? 1 : 0;
+	result = refresh_index(&the_index, (flags), NULL, NULL,
+			       "Unstaged changes after reset:") ? 1 : 0;
 	if (write_cache(fd, active_cache, active_nr) ||
 			commit_locked_index(index_lock))
 		return error ("Could not refresh index");