merge: don't merge detail and non-detail

qbsp/merge.c

@@ -73,7 +73,9 @@ TryMerge(face_t *f1, face_t *f2)
 	f1->planeside != f2->planeside ||
 	f1->texinfo != f2->texinfo ||
 	f1->contents[0] != f2->contents[0] ||
-	f1->contents[1] != f2->contents[1])
+	f1->contents[1] != f2->contents[1] ||
+        f1->cflags[0] != f2->cflags[0] ||
+        f1->cflags[1] != f2->cflags[1])
 	return NULL;
 
     // find a common edge