3a61037733 Retry client should return AlreadySubscribed error (Riccardo Casatta)
Pull request description:
Users may leverage the Error to avoid remembering client-side the subscription status. eg. Always subscribing and calling script_pop in case AlreadySubscribed is returned.
Backport for version 0.14.0
ACKs for top commit:
afilini:
ACK 3a61037733
Tree-SHA512: d6542227ca03b9f3755cec05115f86de54789cfc49fc87b603b653e0458f6b03ae9fea57fa110221395a4e33cf62a5b2bd7639c4269ae5291e4c92c99ef41eba