/usr/lib/python2.7/dist-packages/charmtools/templates/python_services/files/hooks/start is in charm-tools 2.1.2-0ubuntu4.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 | #!/usr/bin/python
import services
services.manage()
|