subscriber cannot recover from history full condition

[liamstask]

using code adapted from the HelloWorld example: https://gist.github.com/liamstask/b1c47a93800be9795697756dcfd00fec (similar to my previous gist here)

I expect to see the subscriber become full once the first 2 messages are sent quickly from the publisher, and then space in its history to be recovered once the publisher starts sending more slowly than the subscriber is reading.

Instead, I see [Warning][SubscriberHistory::add_change] Attempting to add Data to Full ReaderHistory: 0.0.1.4 logged indefinitely.

Taking a look through the implementation, the m_isHistoryFull flag in SubscriberHistory gets set true in several places, but only gets cleared in History::remove_all_changes() which is not called anywhere, so it appears there is no way for Subscriber to be considered not full once it becomes full.