The idea is to keep track of each custom HCoop Debian package using three branches, which are as follows.
upstream: The source code from the current release of the upstream software.
debian: The source code plus the latest Debian packaging that Debian has for the software.
master: The source code plus the latest Debian packaging plus any changes that HCoop has made to the source or the packaging.
If you are creating a native package (e.g. for configuration files) then you only have a master branch.