fix for 2 segfaults running in background mode.

- operators which reload G.main would crash blender if called from python and then accessed bpy.data.*
- WM_read_homefile_exec was setting the contexts Scene to NULL as a signal for the event system, this didnt work in background mode, crashing when property update functions expected scene to be set.

source/blender/python/intern/bpy_operator.c

@@ -231,6 +231,12 @@ static PyObject *pyop_call(PyObject *UNUSED(self), PyObject *args)
 		return NULL;
 	}
 
+	/* when calling  bpy.ops.wm.read_factory_settings() bpy.data's main pointer is freed by clear_globals(),
+	 * further access will crash blender. setting context is not needed in this case, only calling because this
+	 * function corrects bpy.data (internal Main pointer) */
+	BPY_modules_update(C);
+
+
 	/* return operator_ret as a bpy enum */
 	return pyrna_enum_bitfield_to_py(operator_return_items, operator_ret);
 

source/blender/python/intern/bpy_rna.c

@@ -5316,8 +5316,6 @@ static int bpy_class_validate(PointerRNA *dummyptr, void *py_data, int *have_fun
 	return 0;
 }
 
-extern void BPY_modules_update(bContext *C); //XXX temp solution
-
 /* TODO - multiple return values like with rna functions */
 static int bpy_class_call(bContext *C, PointerRNA *ptr, FunctionRNA *func, ParameterList *parms)
 {

source/blender/python/intern/bpy_rna.h

@@ -110,4 +110,6 @@ int pyrna_array_contains_py(PointerRNA *ptr, PropertyRNA *prop, PyObject *value)
 
 int pyrna_write_check(void);
 
+void BPY_modules_update(struct bContext *C); //XXX temp solution
+
 #endif

source/blender/windowmanager/intern/wm_files.c

@@ -429,9 +429,13 @@ int WM_read_homefile(bContext *C, ReportList *reports, short from_memory)
 		BPY_modules_load_user(C);
 	}
 #endif
-	
+
 	WM_event_add_notifier(C, NC_WM|ND_FILEREAD, NULL);
-	CTX_wm_window_set(C, NULL); /* exits queues */
+
+	/* in background mode the scene will stay NULL */
+	if(!G.background) {
+		CTX_wm_window_set(C, NULL); /* exits queues */
+	}
 
 	return TRUE;
 }

source/blender/windowmanager/intern/wm_operators.c

@@ -1350,7 +1350,7 @@ static void WM_OT_read_homefile(wmOperatorType *ot)
 	
 	ot->invoke= WM_operator_confirm;
 	ot->exec= WM_read_homefile_exec;
-	ot->poll= WM_operator_winactive;
+	/* ommit poll to run in background mode */
 }
 
 static void WM_OT_read_factory_settings(wmOperatorType *ot)
@@ -1361,7 +1361,7 @@ static void WM_OT_read_factory_settings(wmOperatorType *ot)
 	
 	ot->invoke= WM_operator_confirm;
 	ot->exec= WM_read_homefile_exec;
-	ot->poll= WM_operator_winactive;
+	/* ommit poll to run in background mode */
 }
 
 /* *************** open file **************** */