Description of problem:
When I set --configdir mock produces an error (see below).


Version-Release number of selected component (if applicable):
0.6.10-1

How reproducible:
Every time

Steps to Reproduce:
1. mock --configdir=$HOME -r '<some_cfg_name>' <my.src.rpm>

  
Actual results:
Traceback (most recent call last):
  File "/usr/bin/mock", line 995, in ?
    main()
  File "/usr/bin/mock", line 941, in main
    if config_path != "/etc/mock" and os.file.exists("/etc/mock/defaults.cfg"):
AttributeError: 'module' object has no attribute 'file'


Expected results:
Working.

Additional info:
Patch attached, just a simple attribute error.