Remove just deleted POP3 messages from the internal maps
This is to prevent attempts to delete them again.
Fixes the testCountBasedLeaveRule, which excercises the following
scenario:
- initial state: 3 messages known
- two new messages are added on server
- LIST returns 5 messages
- UIDL returns 5 UIDs, 2 of them new
- download of 2 messages starts
- fetch of first message is completed
- item create for first message is completed
- item create completion triggers cleanup of unwanted server messages
- messages 1 and 3 are deleted as they are the oldest
- fetch of second message is completed
- item create for second message is completed
- item create completion triggers cleanup of unwanted server messages
- messages 1 and 3 are deleted again - this causes the test to fail
Removing those identifiers causes the second search for items to
delete to return an empty set and no further delete attempts are made.
Reviewers: KDE PIM
Reviewed By: dvratil
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D15975