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.

#!/bin/sh

hg init
echo a > a
hg commit -A -ma

echo a >> a
hg commit -mb

echo a >> a
hg commit -mc

hg up 1
echo a >> a
hg commit -md

hg up 1
echo a >> a
hg commit -me

hg up 1
echo % should fail because not at a head
hg merge

hg up
echo % should fail because \> 2 heads
hg merge

echo % should succeed
hg merge 2
hg commit -mm1

echo % should succeed - 2 heads
hg merge
hg commit -mm2

echo % should fail because 1 head
hg merge

true