If you have some configuration in your modules config/install directory, it didn’t get deleted during module uninstall routine.
drush en -y YOURMODULE will throw an error if you try to reinstall your module. But during development – e.g. custom migrations – you will likely find you in a situation where you have repeatedly to to this. I tried the config_devel module. Sadly without much success.
Luckily since beta3 you can add (change record) enforced dependencies. Since then
drush pmu -y YOURMODULE will uninstall your config item too.
You have to add:
to all of your config files.
drush pmu -y YOURMODULE && drush en -y YOURMODULE will give you a fresh reinstall with all the new config goodness. Not very elegant, but it works.