convert: mercurial_source: also search for copies in modified files There are some corner cases where we may have a copy in a file that isn't in the added list: - the result of a hg copy --after --force - after a merge across a (local) rename

#!/bin/sh
# a test for issue586

hg init a
cd a
echo a > a
hg ci -Ama

hg init ../b
cd ../b
echo b > b
hg ci -Amb

hg pull -f ../a
hg merge
hg rm -f a
hg ci -Amc

hg st -A