Installation
_date=...
_prefix="/packages/hg-git/next--${_date}"
_sources='https://bitbucket.org/durin42/hg-git/get/next.zip'
_python="$( which -- python2.7 )"
mkdir -- "${_prefix}"
virtualenv --python "${_python}" --no-site-packages --distribute --never-download -- "${_prefix}"
"${_prefix}/bin/pip" install "${_sources}"