Fix string test (was testing str twice).
diff --git a/Lib/textwrap.py b/Lib/textwrap.py
index 03b4ea8..e65cdc3 100644
--- a/Lib/textwrap.py
+++ b/Lib/textwrap.py
@@ -125,7 +125,7 @@
         if self.expand_tabs:
             text = text.expandtabs()
         if self.replace_whitespace:
-            if isinstance(text, str):
+            if isinstance(text, str8):
                 text = text.translate(self.whitespace_trans)
             elif isinstance(text, str):
                 text = text.translate(self.unicode_whitespace_trans)