KeyError raised if specified module already installed

[yrro]

It seems --ignore-installed is not passed through to pip:

$ ./peep.py install --user --ignore-installed -r requirements.txt 

The following packages had no hashes specified in the requirements file, which
leaves them open to tampering. Vet these packages to your satisfaction, then
add these "sha256" lines like so:

Traceback (most recent call last):
  File "./peep.py", line 378, in <module>
    exit(main())
  File "./peep.py", line 370, in main
    return commands[argv[1]](argv[2:])
  File "./peep.py", line 343, in peep_install
    print '# sha256: %s' % downloaded_hashes[package_name]
KeyError: 'nose'

$ python
Python 2.7.3 (default, Jan  2 2013, 13:56:14) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import nose
>>> nose
<module 'nose' from '/usr/lib/python2.7/dist-packages/nose/__init__.pyc'>
>>> 

[erikrose]

This should be fixed by our fix to #22. Please reopen if it isn't.