libfuse.File: explicit Sync after a truncate syscall
libfuse.File: explicit Sync after a truncate syscall

A truncate syscall is not necessarily followed by a close, so we need
to sync explicitly.

keybase/kbfs,keybase/client,keybase/client,keybase/kbfs,keybase/kbfs,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client