 expected
(EAGAIN/EWOULDBLOCK is handled correctly by the await-getline!,
await-geteveryline! and await-getsomelines! procedures from version
0.5, and by await-getblock!, await-geteveryblock!,
await-getsomeblocks, await-put-bytevector! and await-put-string!).
Secondly, with select() the file descriptor value of a port passed to
the watch should not exceed FD_SETSIZE.  Normally, by default the
maximum soft user limit for open files is the same as FD_SETSIZE, and
it is best if this situation is retained by us