Using catkin_make_isolated to build Debian packages for a mixed catkin/cmake workspace

I was trying to build a Debian package that contains multiple ROS packages by wrapping `catkin_make_isolated` in a simple Makefile in the root of a workspace that contains catkin and cmake packages. That works quite well, but I had to apply this patch so that catkin generates the environment in the `DESTDIR` prefixed install-space (if the `env.sh` in the real install directory already exists) or does not overwrite catkin-generated setup files (if no `env.sh` file is present in the real install directory). Except of this little problem catkin_make_isolated seems to respect the `DESTDIR` variable set by `dh_auto_install`.

Is there an "official" way to use catkin and/or bloom to generate Debian packages for a whole workspace instead for single packages?