Portion of SF patch #761104. Fixes a minor docstring error.
_TemporarilyImmutableSet is in fact a subclass of BaseSet
diff --git a/Lib/sets.py b/Lib/sets.py
index e6a509f..ebe62c6 100644
--- a/Lib/sets.py
+++ b/Lib/sets.py
@@ -25,10 +25,9 @@
ImmutableSet -- Immutable sets, subclass of BaseSet; hashable.
An iterable argument is mandatory to create an ImmutableSet.
-_TemporarilyImmutableSet -- Not a subclass of BaseSet: just a wrapper
- around a Set, hashable, giving the same hash value as the
- immutable set equivalent would have. Do not use this class
- directly.
+_TemporarilyImmutableSet -- A wrapper around a Set, hashable,
+ giving the same hash value as the immutable set equivalent
+ would have. Do not use this class directly.
Only hashable objects can be added to a Set. In particular, you cannot
really add a Set as an element to another Set; if you try, what is