The current epoch will never advance if there are no other domains

Description

In Cap::_processDone(), it returns if no domains are set, if (domains.length == 0) return;. This means it will be impossible to advance epoch if there are no domains set, which may be fine as the cap can be increased either way.

Recommendation

Consider adding a comment with the intended behaviour or modify it if required.

Status

Addressed in #67aa296.