[Distutils] problem with zc.buildout download-cache setting

[Sydney Weidman]

I have a buildout recipe (zc.buildout 1.3.0) for a Plone site I'm
building and it contains the line:

download-cache = downloads

but I find that when I run bin/buildout, the directory does not get
created and I get the following traceback:

[educommons at vrs OCWBuildout]$ bin/buildout -Uv
While:
  Initializing.
Error: The specified download cache:
'/home/educommons/OCWBuildout/downloads'
Doesn't exist.

The code from zc.buildout.buildout looks like:

        download_cache = options.get('download-cache')
        if download_cache:
            download_cache = os.path.join(options['directory'],
download_cache)
            if not os.path.isdir(download_cache):
                raise zc.buildout.UserError(
                    'The specified download cache:\n'
                    '%r\n'
                    "Doesn't exist.\n"
                    % download_cache)
            download_cache = os.path.join(download_cache, 'dist')
            if not os.path.isdir(download_cache):
                os.mkdir(download_cache)

            zc.buildout.easy_install.download_cache(download_cache)


It seems odd to me that if the download_cache directory doesn't exist,
that UserError is raised. Shouldn't the directory be created? What
would be the harm in that? Or am I missing something?

I realize that I could just mkdir downloads and it would work, but it
seems to defeat the simplicity of "python bootstrap.py; bin/buidout;
bin/instance start".

I'm sure this is some failure of understanding on my part, otherwise
I'm sure someone else would have encountered this issue before.

Regards,
Syd