PBXManager and Reports broken

See thread on mailing list for details but basically, if you try and include the "user" column in a report then it generates an invalid query and fails to run. Happened since at least 6.3.0 and still present now in 7.1.0

http://lists.vtigercrm.com/pipermail/vtigercrm-developers/2018-October/037790.html