.NET 4.6.1 update appears to break 33.7 setup

I was debugging a strange dynamic plugin problem under 34.2 x86 (which I have since fixed), and went back to try it under 33.7 x86. I ran setup.exe and got a red light on .NET 4.5! 34.2 setup.exe showed it as green. I remembered updates doing a .NET update to 4.6, so thought that might be the problem, and uninstalled it.

Then it got really weird where the setup.exe WebSetup button gave me a bad link on the MS site, and searching there for .NET 4.5.2 only gave more dead links. After a while I guess they fixed their problems and the links came back, and reinstalling 4.5.2 fixed the red light problem in 33.7 setup.

So apparently if windoze updates .NET to 4.6, setup.exe for will show .NET 4.5 as not present.

possibly related:
so yes, there’s been a problem with setup.exe of previous versions not correctly detecting the installed version of .net but we can’t fix that for those old versions obviously. for setup.exe of latest b34.2 everything should be fine though.