"Executable does not exist" message after changing of build env settings

I have a simple "Hello" application (please, see an attcahment):

== bug.pro =

TARGET = $$qtLibraryTarget($$TARGET)
TEMPLATE = app
CONFIG -= app_bundle
SOURCES += main.cpp

== main.cpp ==

#include <QCoreApplication>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    qDebug() << "Hello";
    return 0;
}

== .qmake.conf ==

top_sourcedir=$$PWD
top_builddir=$$shadowed($$PWD)

1) When I open a project in first time, compile it in 'debug' target, then it runs successfully when I press the "Run" or "Start Debugging" button. In this case the executable file has the 'd' suffix, i.e. bugd.exe (in debug mode).

2) Next, I try to add e.g. an additionsl env variable (e.g. FOO with value BAR) from the QtC's project build settings (build env).

3) Now, at trying to press the "Run" or "Start Debugging" button, the application does not start, and the QtC prints out following message:

Executable C:\Users\denis\Documents\build-bug-Desktop_Qt_5_9_3_MSVC2015_32bit-Debug\debug\bug.exe does not exist.

I see, that QtC expects the executable name without of 'd' suffix now by a strange reason.

In this case re-building of an opened project (with qmake re-call) does not help... An only one workaround - it is to close and re-open a project again.

It is interest, that if I remove the .qmake.conf file, then all works as expected. 

I have not remember this behavior in previous QtC versions (as 4.6.0, 4.5.x), I faced with this issue only in QtC 4.6.1.