Build with MSVC 2012 32 Bit Qt 4.8 fails

I cloned the current (5f0f5dd371cb5fbd1ae1cb8f7b6f03c0109d2d6c) qt 4.8 branch.
Then I modified the win32-msvc2012 qmake.conf (s/MD(d?)/MT$1/g) as described in the INSTALL file.
I used the recommended configure line and then built qt. So far everything worked.

Now I cloned the installer framework 1.6 branch (def65ef3cc54651192c676fc1b9ccfe567bc1a79).
qmake && nmake

The compilation works but then the linker complains:
link /LIBPATH:"c:\qt-4.8\lib" /LIBPATH:"c:\qt-4.8\lib" /NOLOGO /DYNAMICBASE /NXCOMPAT /INCREMENTAL:NO /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='' processorArchitecture=''" /OUT:..\..\bin\installerbase.exe @C:\Users\FELIXB~1\AppData\Local\Temp\nmFD52.tmp
LINK : fatal error LNK1181: Eingabedatei "C:\qt-4.8\plugins/imageformats\qicod.lib" kann nicht geöffnet werden.

The error (German) basically says the qicod.lib plugin could not be opened.
Okay, I only built the release libs of qt (as the INSTALL file of the installer framework suggests), so the debug libs should obviously be missing.

But I wonder why the installer framework would depend on a debug plugin.

I also tried an explicit "nmake release" but that resulted in the same error.