Fetch another batch of initial messages if a whole batch was received.
Fetch another batch of initial messages if a whole batch was received.

Fixes #1395 where only the first batch was loaded initially.

Signed-off-by: Joachim Bauch <f7be0a2a0fb4eba859c8fa4289260059dc564a0d@struktur.de>

nextcloud/spreed,nextcloud/spreed,nextcloud/spreed