mingw: tool commands have no path separator between qt bin dir and command name

OK, I've managed to reproduce this on Windows XP with Qt 4.7 beta 1, and Win 7 Qt 4.6.2
This is Qt problem. qmake generates invalid makefile, without any path
separator at all between "bin" and tool name ("uic", "idc", "moc").

E.g. I see the following buggy lines in the makefile produced by qmake:

> IDC = c:/util/qt-4.7b1/binidc.exe
> ...
> ui_HelloForm.h: HelloForm.ui
> c:/util/qt-4.7b1/binuic.exe HelloForm.ui -o ui_HelloForm.h

This is without NetBeans at all, pure command line.

Yet another clarification: the bug is triggered by "CONFIG-=debug_and_release".
Without this qmake generates Makefile.Release and Makefile.Debug, both with
correct paths.