heroku/heroku-buildpack-python — pull request #123 by pkatseas (2014-03-03 21:21:25+00:00)
Title: Process dependency links

This change allows external packages specified via the dependency_links attribute in `setup.py` files to be properly installed when using pip 1.5.
`--allow-all-external` was found to not affect this situation at all. If problems with unverified packages arise, the `--allow-unverified PACKAGE_NAME` is necessary anyway, which includes the `--allow-external PACKAGE_NAME` flag.