Mercurial：在初始提交后排除django settings.py

In my Django project, I want the settings.py file to be included in the initial commit so that other developers can clone the repository and change the original settings to work with there local setup. But, after that I don't want to manually exclude the file at every commit, and the ignore file wont work because it's already tracked.In my Django project, I want the settings.py fi