Fix theoretical issue in filecommit.
If the file was copied, we don't want to reuse the original entry.
I think this is mostly a theoretical issue - when there are copies,
fp1 == nullid, so it's very unlikely that the fl.cmp(fp1, t) would
think the file was unmodified. In any case, if there was a copy,
we should forcefully create a new entry.
#!/bin/sh
hg init dir
cd dir
echo bleh > bar
hg add bar
hg ci -m 'add bar'
hg cp bar foo
echo >> bar
hg ci -m 'cp bar foo; change bar'
hg debugrename foo
hg debugindex .hg/store/data/bar.i