regression: serve-branches doesn't accept path argument

Small regression in trunk where if I run

./serve-branches .

I get the following:

/home/pbui/src/other/loggerhead/trunk/loggerhead/search.py:20: DeprecationWarning: the sets module is deprecated
  import sets
Traceback (most recent call last):
  File "./serve-branches", line 149, in <module>
    main(sys.argv)
  File "./serve-branches", line 47, in main
    [path] = args
ValueError: too many values to unpack

One line fix is attached.