Commit 9ea06c01ba introduced some clean-up in tag fetching. Unfortunately with it came a regression which caused tags not to be fetched as part of notifications - no matter how the fetch scope is configured.
The problem lies in the fact that the FetchHelper class, which populates items based on the configured fetch scope still uses the Tags flag in the item fetch scope to determine if tags should be fetched at all and only if this flag is set the tag fetch scope is examined to determine what tag information to include.
On the notification side however support for handling this flag in the AggregatedItemFetchScope was removed, which causes the flag never to be set for the item fetch scope, which in turn means that no tags will ever be fetched for notifications regardless of tag fetch scope setting.
This commit brings back handling of the Tags flag in the item fetch scope thereby partially reverting commit 9ea06c01ba.
No autotests exist that cover this functionality. There is a Akonadi::Monitor test, but it does not test any tags and it looks like adding this would require supporting tags in knutresource, which is currently also missing.
Unfortunately it seems like the EWS resource is the only one that is really using tags and all the bugs eventually land on my table ;)