qmake: $$files() expands with backslashes on win32

Place baz.cpp on foo/bar, then add this to the pro file:

SOURCES += $$files(foo/bar/*.cpp)
message($$SOURCES)

The output will be foo\bar/baz.cpp. It is expected to be foo/bar/baz.cpp (i.e. remove a file using SOURCES -= foo/bar/unneeded.cpp)