Bug 977384 - mach mercurial-setup: Refactor part 1; r=gps
Bug 977384 - mach mercurial-setup: Refactor part 2; r=gps
Bug 977384 - mach mercurial-setup: Remaining cleanup; r=gps
Bug 977414 - mach mercurial-setup: Fix hgrc paths for extensions on Windows; r=gps