I finally took the time to make my 'drupaldev'-repository available.
First a short introduction: It is my strong opinion that Drupal modules which are only used during development, such as devel, diff, etc, should never be deployed to production. They shouldn't even be in the repository. Instead, I keep a personal collection of development-modules in a separate repo. Thanks to the fact that Drupal recursively searches for modules inside the modules folder, I can simply create a symlink to my collection of development modules. This allows me to use my preferred modules, even though they are not in the repository for the project.
For Drupal7, I usually just create a symlink, named devmodules7, in sites/all/modules. Like this:
# from the drupal root of the project
ln -s ~/drupaldev/devmodules7 sites/all/modules/
The repository itself contains a collection of modules, for both Drupal 6 and Drupal 7, and some utility-scripts. After experimenting with copies of the modules and git submodules, I finally settled on drush make to manage the …