bpo-40824: Do not mask errors in __iter__ in "in" and the operator module. (GH-20537)


Unexpected errors in calling the __iter__ method are no longer
masked by TypeError in the "in" operator and functions
operator.contains(), operator.indexOf() and operator.countOf().
(cherry picked from commit cafe1b6e9d3594a34aba50e872d4198296ffaadf)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Objects/abstract.c b/Objects/abstract.c
index 5b85b01..1d671c9 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -2058,7 +2058,9 @@
 
     it = PyObject_GetIter(seq);
     if (it == NULL) {
-        type_error("argument of type '%.200s' is not iterable", seq);
+        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            type_error("argument of type '%.200s' is not iterable", seq);
+        }
         return -1;
     }