Revert "Cannot use WL_SOCKET_WRITEABLE without WL_SOCKET_READABLE."
This reverts commit
3a9e64aa0d96c8ffb6c682b082d0f72b1d373327.
Commit
4bad60e3 fixed the root of the problem that
3a9e64aa worked
around.
This enables proper pipelining of commands after terminating
replication, eliminating an undocumented limitation.
Discussion: https://postgr.es/m/
3d57bc29-4459-578b-79cb-
7641baf53c57%40iki.fi
Backpatch-through: 9.5