beam.Copy doesn't return an error on EOF
beam.Copy doesn't return an error on EOF

Signed-off-by: Solomon Hykes <510d74b69d9d43b60b6f6aa9d95e9f9c9497f815@docker.com>

beni55/libchan,docker/libchan,wangtuanjie/libchan,dmcgowan/libchan