rebase -i: move unlink() calls

rebase -i: move unlink() calls

At the start of each iteration the loop that picks commits removes the
state files from the previous pick. However some of these files are only
written if there are conflicts in which case we exit the loop before the
end of the loop body. Therefore they only need to be removed when the
rebase continues, not at the start of each iteration.

Signed-off-by: Phillip Wood <redacted>
Signed-off-by: Junio C Hamano <redacted>