fix_holonomic caching error

iammosespaulr · iammosespaulr · commit 1406c094fcec · 2020-05-01T20:09:43.000+05:30
diff --git a/sympy/holonomic/holonomic.py b/sympy/holonomic/holonomic.py
@@ -2807,7 +2807,7 @@ def _shift(func, s):
         a = d[b]
 
         t = b.as_base_exp()
-        b = t[1] if t[0] is x else S.Zero
+        b = t[1] if t[0] == x else S.Zero
         r = s / b
         an = (i + r for i in func.args[0][0])
         ap = (i + r for i in func.args[0][1])
