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
hg init
echo a > a
hg ci -Am t
hg mv a b
hg ci -Am t1
hg debugrename b
hg mv b a
hg ci -Am t2
hg debugrename a
echo % test with --rev
hg debugrename --rev 1 b