Oops...that will teach me to hit ^C^C too fast.  Test passed.
diff --git a/Lib/regsub.py b/Lib/regsub.py
index 7778602..de833d5 100644
--- a/Lib/regsub.py
+++ b/Lib/regsub.py
@@ -110,7 +110,7 @@
     words = splitx(str, pat)
     for i in range(0, len(words), 2):
         words[i] = words[i].capitalize()
-    return "".joinfields(words)
+    return "".join(words)
 
 
 # Internal subroutines: