QtWebEngine get not compiled with Windows 10 and MSVC 2015 RTM

When I try to compile QtWebEngine, it prints an Error like "QtWebEngine can only be build with Linux, Windows (MSVC 2013) ... - WebEngine will not be built."

The configure Parameter are as follows:

c:\qt5src\configure -opensource -confirm-license -prefix d:\qt-build
-opengl dynamic -debug-and-release -developer-build
-openssl -I C:\opensslx32\include -L c:\opensslx32\lib -mp -skip webkit
-nomake tests -nomake examples

All additional Tools like PSCP from PuTTy are installed and in the System Environment Path.

Is it possible to have a fix for it in 5.5.1? That would be great. I just started to move from WebKit to WebEngine and now it does not get build. (Yes there are pre-compiled MSVC 2013 Packages - but I have some OpenSSL Stuff in my App.)

In Addition: I have lost 12 hours today figuring out why WebEngine always got skipped. A fix for that (some Error Messages) would be nice too.

[I had Python 3.4 installed (which I use on every Qt Version since 5.2.0 - never had a Problem). But WebEngine says "Python Version '*,' is installed but >2 [2.7] is required. It will not compile with Python 3.4 also. I went back to the latest 2.7 ActivePython available after all. Then it finally gave me the above mentioned Build Error Message]

Thanks
Oliver