fixes 0003771: Memory leak in Part.Face.Surface

src/Base/PyObjectBase.cpp

@@ -177,7 +177,8 @@ PyObject* PyObjectBase::__getattro(PyObject * obj, PyObject *attro)
     PyObject* value = pyObj->_getattr(attr);
 #if 1
     if (value && PyObject_TypeCheck(value, &(PyObjectBase::Type))) {
-        if (!static_cast<PyObjectBase*>(value)->isConst()) {
+        if (!static_cast<PyObjectBase*>(value)->isConst() &&
+            !static_cast<PyObjectBase*>(value)->isNotTracking()) {
             static_cast<PyObjectBase*>(value)->setAttributeOf(attr, pyObj);
             pyObj->trackAttribute(attr, value);
         }

src/Base/PyObjectBase.h

@@ -201,7 +201,8 @@ class BaseExport PyObjectBase : public PyObject
     enum Status {
         Valid = 0,
         Immutable = 1,
-        Notify = 2
+        Notify = 2,
+        NoTrack = 3
     };
 
 protected:
@@ -313,6 +314,14 @@ public:
 
     void startNotify();
 
+    void setNotTracking(bool on=true) {
+        StatusBits.set(NoTrack, on);
+    }
+
+    bool isNotTracking() const {
+        return StatusBits.test(NoTrack);
+    }
+
     typedef void* PointerType;
 
 private: