I use virtualenv to create isolated environments for my Python projects. Then i install dependencies with pip - Python package manager. Sometimes i forget to do source venv/bin/activate, and then pip creates build/ directories inside my projects. Why does pip create them? May i delete them, and if not, may i put them in my .hgignore file? As far as i understand, pip stores source of downloaded packages there along a file called pip-delete-this-directory.txt. But when i delete it, everything still works, as the real code is being put into venv/lib/python2.7/site-packages/. Then what is build/ really for? Continue reading...