fs: Setattr seeing flag SetattrHandle set is not an error
fs: Setattr seeing flag SetattrHandle set is not an error

The flag just means SetattrRequest.Handle is valid.
This triggers with e.g. `ftruncate(fd, 42)`:

    dd if=/dev/zero of=foo bs=1 count=1 seek=42

bazil/bazil,lisael/bazil