Can't import content type with two underscores in a row

While trying to import a content type (from another server) which I had named "c__monthly_review", I kept getting this message:

The machine-readable name must contain only lowercase letters, numbers, and underscores.

So, I traced the issue to the fact that I had 2 underscores in a row after the "c" in my machine name.

It comes from line 348 of the .module file.

To let me perform the import, I simply changed the line to this:

$machine_name = preg_replace('@[^a-z0-9]@', '_', strtolower($bundle_name));  // Removed the +, so it doesn't replace more than one occurance.

This may not work for everyone, but I thought it worth noting, in the hopes that others might find this one day.