In a similar bug related to OF-38 there is an Unsubscribe loop:
The client’s “affirmation” unsubscribe message is routed to the contact by the server per the RFC.
Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence
Section 8.4.1 Step 7
"Upon receiving the presence stanza of type “unsubscribed”, the user SHOULD acknowledge receipt of that subscription state notification through either “affirming” it by sending a presence stanza of type “unsubscribe” to the contact or “denying” it by sending a presence stanza of type “subscribe” to the contact; this step does not necessarily affect the subscription state (see Subscription States for details), but instead lets the user’s server know that it MUST no longer send notification of the subscription state change to the user (see Section 9.4). "
However, this causes the some client software to begin the Unsubscribe process again. In OF-38 an adjustment was made to have the server “eat” the subscribe “affirmation” message. This is probably a suitable change for the unsubscribe issue as well. If the change is not made the client and contact enter into an infinite unsubscrbe loop until one of them disconnect.
I have verified the following software will enter into the loop:
MomentIM
Jabber.net Library