SF patch #440144: Tests and minor bugfix for uu module

decode():  While writing tests for uu.py, Nick Mathewson discovered
that the 'Truncated input file' exception could never get raised,
because its "if not str:" test was actually testing the builtin
function "str", not the local string vrbl "s" as intended.

Bugfix candidate.

Lib/uu.py

@@ -135,7 +135,7 @@ def decode(in_file, out_file=None, mode=None):
             sys.stderr.write("Warning: %s\n" % str(v))
         out_file.write(data)
         s = in_file.readline()
-    if not str:
+    if not s:
         raise Error, 'Truncated input file'
 
 def test():