diffcore-rename: fix merging back a broken pair.

When a broken pair is matched up by rename detector to be merged
back, we do not want to say it is "dissimilar" with the
similarity index.  The output should just say they were changed,
taking the break score left by the earlier diffcore-break run if
any.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diffcore-rename.c

@@ -54,12 +54,14 @@ static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
 /* Table of rename/copy src files */
 static struct diff_rename_src {
 	struct diff_filespec *one;
+	unsigned short score; /* to remember the break score */
 	unsigned src_path_left : 1;
 } *rename_src;
 static int rename_src_nr, rename_src_alloc;
 
 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
-						   int src_path_left)
+						   int src_path_left,
+						   unsigned short score)
 {
 	int first, last;
 
@@ -89,6 +91,7 @@ static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
 		memmove(rename_src + first + 1, rename_src + first,
 			(rename_src_nr - first - 1) * sizeof(*rename_src));
 	rename_src[first].one = one;
+	rename_src[first].score = score;
 	rename_src[first].src_path_left = src_path_left;
 	return &(rename_src[first]);
 }
@@ -198,7 +201,10 @@ static void record_rename_pair(int dst_index, int src_index, int score)
 	fill_filespec(two, dst->sha1, dst->mode);
 
 	dp = diff_queue(NULL, one, two);
-	dp->score = score;
+	if (!strcmp(src->path, dst->path))
+		dp->score = rename_src[src_index].score;
+	else
+		dp->score = score;
 	dp->source_stays = rename_src[src_index].src_path_left;
 	rename_dst[dst_index].pair = dp;
 }
@@ -256,10 +262,10 @@ void diffcore_rename(struct diff_options *options)
 			 * that means the source actually stays.
 			 */
 			int stays = (p->broken_pair && !p->score);
-			register_rename_src(p->one, stays);
+			register_rename_src(p->one, stays, p->score);
 		}
 		else if (detect_rename == DIFF_DETECT_COPY)
-			register_rename_src(p->one, 1);
+			register_rename_src(p->one, 1, p->score);
 	}
 	if (rename_dst_nr == 0 || rename_src_nr == 0 ||
 	    (0 < rename_limit && rename_limit < rename_dst_nr))