Discourse's general category permissions could be set back to default

Discourse is an open source discussion platform. Prior to version 3.0.4 of the `stable` branch and version 3.1.0.beta5 of the `beta` and `tests-passed` branches, if a site has modified their general category permissions, they could be set back to the default. This issue is patched in version 3.0.4 of the `stable` branch and version 3.1.0.beta5 of the `beta` and `tests-passed` branches. A workaround, only if you are modifying the general category permissions, is to use a new category for the same purpose.