SF bug [#473864] doctest expects spurios space.

Repair unlikely surprise due to magical softspace attr and the use of
print with a trailing comma in doctest examples.
Bugfix candidate.

Lib/doctest.py

@@ -379,9 +379,15 @@ class _SpoofOut:
         # that a trailing newline is missing.
         if guts and not guts.endswith("\n"):
             guts = guts + "\n"
+        # Prevent softspace from screwing up the next test case, in
+        # case they used print with a trailing comma in an example.
+        if hasattr(self, "softspace"):
+            del self.softspace
         return guts
     def clear(self):
         self.buf = []
+        if hasattr(self, "softspace"):
+            del self.softspace
     def flush(self):
         # JPython calls flush
         pass