While most users will likely typically call uv_close in their
uv_shutdown callback, some callers (notable nodejs) do not always do
so. This can result in libuv keeping the loop active, even though there
are no outstanding reqs left to handle.
This bug was added in 80f2f826bf, where
the premise of that commit appears to have simply been incorrect, as
demonstrated by the added test.
Refs: https://github.com/libuv/libuv/issues/3202
PR-URL: https://github.com/libuv/libuv/pull/3233
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
