I made a f# script based on the msdn documentation on how to detect which .Net version is installed, results:
v4.0 Client 126.96.36.199
v4 Full 4.6.00057 Client 4.6.00057
v3.5 3.5.30729.4926 SP1
v3.0 3.0.30729.4926 SP2
v2.0.50727 2.0.50727.4927 SP2
System.Version = 4.0.30319.0
dotNetVersion = “4.6 RC or later”
And as mentioned earlier 45beta33.3 setup -> .Net 4.5 = red while 50alpha33.9 setup is green.
So it seems either the XP fix changed behaviour even on other systems or something else changed as well?