Replace Python std output only for GUI application and not for CLI

src/Base/Interpreter.cpp

@@ -343,15 +343,20 @@ const char* InterpreterSingleton::init(int argc,char *argv[])
         Py_Initialize();
         PySys_SetArgv(argc, argv);
         PythonStdOutput::init_type();
-        PythonStdOutput* out = new PythonStdOutput();
-        PySys_SetObject("stdout", out);
-        PySys_SetObject("stderr", out);
         this->_global = PyEval_SaveThread();
     }
 
     return Py_GetPath();
 }
 
+void InterpreterSingleton::replaceStdOutput()
+{
+    PyGILStateLocker locker;
+    PythonStdOutput* out = new PythonStdOutput();
+    PySys_SetObject("stdout", out);
+    PySys_SetObject("stderr", out);
+}
+
 int InterpreterSingleton::cleanup(void (*func)(void))
 {
     return Py_AtExit( func );

src/Base/Interpreter.h

@@ -193,6 +193,7 @@ public:
     /// init the interpreter and returns the module search path
     const char* init(int argc,char *argv[]);
     int  runCommandLine(const char *prompt);
+    void replaceStdOutput();
     static InterpreterSingleton &Instance(void);
     static void Destruct(void);
     //@}

src/Gui/Application.cpp

@@ -1403,6 +1403,7 @@ static void init_resources()
 void Application::initApplication(void)
 {
     try {
+        Base::Interpreter().replaceStdOutput();
         initTypes();
         new Base::ScriptProducer( "FreeCADGuiInit", FreeCADGuiInit );
         init_resources();