r2977 breaks setup

[Markus Tacker <m@…>]

r2977 has broken setup. Errors reported include:

• source:trunk/trac/ticket/api.py
• source:trunk/trac/env.py
• source:trunk/trac/scripts/admin.py

Traceback (most recent call last):
  File "/usr/bin/trac-admin", line 21, in ?
    from trac.scripts.admin import run
  File "/usr/lib/python2.4/site-packages/trac/scripts/admin.py", line 33, in ?
    from trac.ticket.model import *
  File "/usr/lib/python2.4/site-packages/trac/ticket/__init__.py", line 1, in ?
    from trac.ticket.api import *
  File "/usr/lib/python2.4/site-packages/trac/ticket/api.py", line 19, in ?
    from trac import util
ImportError: cannot import name util

[anonymous]

Duplicate of #2852.