use copy(self) rather than self.copy()

src/sage/matrix/matrix2.pyx

@@ -13012,7 +13012,7 @@ cdef class Matrix(Matrix1):
         if not self.is_hermitian():
             raise ValueError("matrix is not Hermitian")
 
-        A = self.copy()
+        A = copy(self)
         D = identity_matrix(F, n)
         row = 0