nmake gives a wrong source file to the compiler

Unpack the attached archive,

• cd inside the tools\dummy folder
• qmake
• nmake

Then nmake gives the wrong main_window.cpp source file to cl.exe.
It should be tools\dummy\main_window.cpp but it's ..\..\src\ui\main_window.cpp.

Is it qmake that generates a wrong Makefile or nmake that fails to correctly interprets the Makefile ?

Note that with linux g++/make (gcc 4.4.3) there is no problem.