/dev/fuse writes sometimes return ENOENT

[tv42]

With some debugging added, and running a tight loop, I've seen a syscall.Write to the fuse fd fail with ENOENT. Quick skim of kernel code says this happens when e.g. the message id being responded to has been aborted, or the fuse connection has been shut down.

Note that current debug logging is only on the respond path, not on the respondData path.

This seems fickle to reproduce, 10000 runs without an error is completely typical for me.