has errors but Ping continues to trigger syncs for it; added
ProcessLoopDetection for the case where Ping sees state errors for a
synched folder, triggers a sync but the folder is not being
synchronized.
In both cases Ping will invoke a FolderSync (status 7) instead of
sending fake changes. FolderSync will check the relation between the
hierarchy cache and synched data information and remove states of
folders that are not in the hierarchycache anymore.

Released under the Affero GNU General Public License (AGPL) version 3.