Merge pull request #12256 from eric-wieser/patch-3

Keep trailing commas for tuple subclasses of length 1

IPython/lib/pretty.py

@@ -638,7 +638,7 @@ def inner(obj, p, cycle):
                 p.text(',')
                 p.breakable()
             p.pretty(x)
-        if len(obj) == 1 and type(obj) is tuple:
+        if len(obj) == 1 and isinstance(obj, tuple):
             # Special case for 1-item tuples.
             p.text(',')
         p.end_group(step, end)