JBIDE-18806 seems like the expected behaviour (8.0.1.CR1 falls back to 8.0.0) is not working, so try workaround using explicit definition for 8.0.1.CR1 >> master

No. 
Need 4.2.1.CR1 (or 8.0.1.CR1) in order to be able to set staging URLs for QE. 
4.2 (or 8) is the fallback for released milestones.

We DO need to keep updating this because we keep releasing new milestones, which are staged in a different place than the released stuff.