When uploading a ruby gem package, I forgot to use -C, and got:

Since ruby-$_gemname is not in CCR yet, you must provide a category.

The head of the PKGBUILD looks like this:

_gemname=msgpack
pkgname=ruby-$_gemname

I know why this happens, and I'm not sure if there is an easy/good way to fix it.
Priority: Low.