merge: fix small bug with a failed merge across a rename If $HGMERGE wasn't able to fix the conflicts, we wouldn't copy f to fd, and util.set_exec wouldn't find the file.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m "test" -d "1000000 0"
hg verify
hg parents
hg status
hg rollback
hg verify
hg parents
hg status