Merge pull request #37 from ComboProblem/t/31308/interactive_simplex_…

…method__make_it_safe_to_copy_dictionaries

interactive_simplex_method - making copy method safe -  update

src/sage/numerical/interactive_simplex_method.py

@@ -3914,6 +3914,22 @@ def __init__(self, A, b, c, objective_value,
         self._AbcvBNz = [A, b, c, objective_value, B, N, SR(objective_name)]
 
     def __copy__(self):
+        r"""
+        TESTS::
+            sage: A = ([1, 1], [3, 1])
+            sage: b = (1000, 1500)
+            sage: c = (10, 5)
+            sage: P = InteractiveLPProblemStandardForm(A, b, c)
+            sage: D = P.initial_dictionary()
+            sage: D_2 = copy(D)
+            sage: D is D_2
+            False
+            sage: D.enter('x1')
+            sage: D.leave('x3')
+            sage: D.update()
+            sage: D_2 == D
+            False
+        """
         return type(self)(*self._AbcvBNz)
 
     @staticmethod