Avoid some false positives for addremove -s The original code uses the similary score 1 - len(diff(after, before)) / len(after) The diff can at most be the size of the 'before' file, so any small 'before' file would be considered very similar. Removing an empty file would cause all files added in the same revision to be considered copies of the removed file. This changes the metric to bytes_overlap(before, after) / len(before + after) i.e. the actual percentage of bytes shared between the two files.

foo renamed from bar:26d3ca0dfd18e44d796b564e38dd173c9668d3a9
   rev    offset  length   base linkrev nodeid       p1           p2
     0         0       6      0       0 26d3ca0dfd18 000000000000 000000000000
     1         6       7      1       1 d267bddd54f7 26d3ca0dfd18 000000000000