mkspec win32-msvc2012 doesn't work

It looks like the recent added spec for vs2012 (Visual Studio 2012) doesn't work.

Reproduce steps:
1 Get latest code from git://gitorious.org/qt/qt.git, to C:\qt4.8
2 Switch to "branch 4.8"
4 Open a vs2012 command line
5 Navigate to C:\qt4.8
6 Configure and build using command:
configure.exe -opensource -confirm-license -platform win32-msvc2012

Then will get error messages:

Running syncqt...
Creating qmake...
Makefile:12: *** missing separator. Stop.
Makefile:12: *** missing separator. Stop.
Cleaning qmake failed, return code 2

Note:
1 win32-msvc2010 works with qt4.8 branch
2 win32-msvc2012 works with qt5 (qtbase)