[PATCH] Teach diff-tree-helper to handle unmerged paths.

This teaches diff-tree-helper to call diff_unmerge() so that it can
report unmerged paths to GIT_EXTERNAL_DIFF, instead of consuming it on
its own. 

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff-tree-helper.c

@@ -56,7 +56,7 @@ static int parse_diff_tree_output(const char *buf,
 
 	switch (*cp++) {
 	case 'U':
-		fprintf(stderr, "warning: unmerged path %s\n", cp+1);
+		diff_unmerge(cp + 1);
 		return WARNED_OURSELVES;
 	case '+':
 		old->file_valid = 0;