Fix race detected by race detector and error on unreachable code
Fix race detected by race detector and error on unreachable code

Do Tattach synchronously; it can change Msize and that made the race detector
very unhappy.

Remove unreachable panic that go tools complain about now.

Signed-off-by: Ronald G. Minnich <f569d0af9a3481c4007b95c7180d6c41009f2513@gmail.com>

edahlgren/go9p,lionkov/ninep