error: 'egg_base' must be a directory name (got python)

[nbmurphy]

This issue is similar to the one discussed here
pypa/setuptools#1136
and here
pypa/pip#5732
It seems to only effect Python 2.7. Commenting out the line - '2.7' in .travis.yml fixes the problem. However, some repos still use Python 2.7, such as sdss_install through sdss4install, so this is not an ideal workaround.

[albireox]

So, this problem seem to be caused by having a from __future__ import unicode_literals in setup.py. The issue is related to setuptools and I don't think it has been solved. Given that we don't really use any character that is not ASCII in setup.py I think it's safe to remove that import from that file. I've tagged a new version.