Bug fixed:

When we do the "=" operation, the link will be copy to the new tensor instead of replace it.

source/tensor/XTensor.cpp

@@ -397,7 +397,7 @@ XTensor& XTensor::operator= (const XTensor& tensor)
         CheckNTErrors(outgo.tailNum == 0, "The node has outgoing edge to other nodes!");
 
         /* create tensor links for the new tensor */
-        XLink::Replace(&tensor, this);
+        XLink::Copy(&tensor, this);
     }
 
     return *this;
@@ -445,7 +445,7 @@ XTensor& XTensor::operator= (const XTensor&& tensor)
        This is VERY tricky and there might be better solutions :) */
     *tensor.dataP = NULL;
 
-    XLink::Replace(&tensor, this);
+    XLink::Copy(&tensor, this);
 
     return *this;
 }