Two out of three builds for a project I own using the experimental Mono upgrade and 2017.2f1 seem to deadlock after certain steps in Unity Cloud build, causing a lot of the builds to be canceled due to running for too long.
The last log message sent before it deadlocks is “Cleanup mono” and most commonly happens after running unit tests.
Local builds seem to work just fine: it’s only Cloud Builds that seem to fail.
Still discussing / investigating with the Scripting team. I realize it’s a huge impediment and we’re hoping to get this resolved as quickly as possible.