Fix issue with Python debugger when leaving application

src/Gui/PythonConsole.cpp

@@ -1235,7 +1235,9 @@ QString PythonConsole::readline( void )
     this->_sourceDrain = &inputBuffer;     //< enable source drain ...
     // ... and wait until we get notified about pendingSource
     QObject::connect( this, SIGNAL(pendingSource()), &loop, SLOT(quit()) );
-    loop.exec();
+    // application is about to quit
+    if (loop.exec() < 0)
+        inputBuffer = QLatin1String("quit()");
     this->_sourceDrain = NULL;             //< disable source drain
     return inputBuffer.append(QChar::fromAscii('\n')); //< pass a newline here, since the readline-caller may need it!
 }