btrfs: incremental send after replacing a file

btrfs: incremental send after replacing a file

Test that an incremental send works after a file from the parent snapshot
gets replaced in the send snapshot by another one at the same exact
location, with the same name and with the same inode number.

This test used to fail after the linux kernel commit 8b191a684968
("Btrfs: incremental send, check if orphanized dir inode needs delayed
rename") and it's fixed by patch titled:

  "Btrfs: send, fix corner case for reference overwrite detection"

Signed-off-by: Martin Raiber <martin@urbackup.org>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>