building requires network for setuptools-darcs, not documented

[gdt]

I tried to build py-zfec from pkgsrc and found that the build step goes to the net to obtain setuptools-darcs. On the build machine, that hung, perhaps due to some IPv6 oddness. The README does not explain that a network connection is needed to install this package.

(PS: trac doesn't really seem set up, but there are so few tickets that seems fine. Let me know if I should be posting these in tahoe trac instead.)

[gdt]

I've worked around this by commenting out:

setup_requires.append('setuptools_darcs >= 1.1.0')

Perhaps all the darcs stuff should only be enabled if some environment variable is set, so that released tarballs don't try to load them? This would be like how programs that use autoconf don't require the user to have autoconf installed.

[gdt]

This problem also exists in zbase32, but that doesn't have a functioning trac.