How to turn a package into something pip can install

[Roy Smith]

In article <roy-8299B9.17014115022014 at news.panix.com>,
 Roy Smith <roy at panix.com> wrote:

> > > $ pip install --no-index --quiet --find-links packages metar==1.4.0
> > [snip]
> > > ValueError: unknown url type: packages
> > 
> > The path to your cache directory is incorrect.  I suggest using
> > absolute paths (eg. /home/user/packages) instead of relative paths,
> > which is likely what caused this issue.
> 
> No, that's not it.  It doesn't work with an absolute path either.

OK, I figured this out.  The on-line docs 
(http://www.pip-installer.org/en/latest/reference/pip_wheel.html) say 
you can give --find-links a path, but it looks like it insists on it 
being a valid URL.  If I prepend "file:" to the absolute path, it works.

Maybe this is something which has changed in newer versions of pip?  
I've got 1.1 (and python 2.7.3).  I'm pretty sure both of these are what 
came with Ubuntu Precise.