ProParser crashes due to unexpected resource file name as input

Creator has a Kit pointing to a (rather old) Qt 4 build.
It aborts at startup. Output is (including qDebug() of the offending file name:
C:/Users/christian/dev/qt-4.8-oslo/mkspecs/features/
C:/Users/christian/dev/qt-4.8-oslo/mkspecs/win32-msvc2008/features/
C:/Users/christian/dev/qt-4.8-oslo/mkspecs/features/
/mkspecs/features/
C:/Users/christian/dev/qt-4.8-oslo/mkspecs/features/spec_pre.prf
c:/Users/christian/bin/sh.exe
:/qmake/features/sh.exe
ASSERT: "fileName.isEmpty() || isAbsolutePath(fileName)" in file C:\Users\christian\dev\qtcreator-3.2\src\shared\proparser\ioutils.cpp, line 50