You used the egg files install procedure.
This procedure supports installing over git, git+http, git+https, git+ssh, git+git and git+file. Some of these are mentioned in other answers.
It's good you. You can use branches, tags, or hashes to install.
@Steve_K notedSteve_K noted it can be slow to install with "git+" and proposed installing via zip file:
pip install https://github.com/user/repository/archive/branch.zip
pip install https://github.com/user/repository/archive/branch.zip
Alternatively, I suggest you may install using the .whl file if this exists.
pip install https://github.com/user/repository/archive/branch.whl
It's pretty new format, newer than egg files. It requires wheelwheel and setuptools>=0.8setuptools>=0.8 packages. You can find more in herethe documentation.