If /proc/self/fd/X did not exist, the actual error is that the file
descriptor was invalid.
go-fuse's pathfs prefers using an open fd even for path-based operations
but does not take any locks to prevent the fd from being closed.
Instead, it retries the operation by path if it get EBADF. So this
change allows the retry logic to work correctly.
This fixes the error
rsync: failed to set times on "/tmp/ping.Kgw.mnt/linux-3.0/[...]/.dvb_demux.c.N7YlEM":
No such file or directory (2)
that was triggered by pingpong-rsync.bash.
Just presenting an empty directory means that the user does not know
that things went wrong unless he checks the syslog or tries to delete
the directory.
It would be nice to report the error even if only some files were
invalid. However, go-fuse does not allow returning the valid
directory entries AND an error.
