Sounds like a reasonable change, especially it out seems to work for you and fixes the issue. Just in case, I’ll run it my someone from the team, here who knows more about MSBuild, but I’ve tentatively committed this change for vNext.
thanx!
Im not willing to manipulate with your original installation. Even if this works for me, it might not be complete solution. Ill wait for your investigation results and fix. Till then, we stay on Legacy.targets.
This change in in 2517, FWIW
Good news, looks all great in .2525 
glad to hear!