ames: don't give %done on cork
Locally, %cork is guaranteed to succeed instantly. The requesting vane
doesn't need an ack to safely consider the flow "closed".
::
?- -.u.cur
%ok
- =. message-pump (give %done current.state ~)
- =? message-pump cork (give %cork ~)
+ =. message-pump
+ :: don't give %done for corks
+ ::
+ ?: cork (give %cork ~)
+ (give %done current.state ~)
$(current.state +(current.state))
::
%nack
