Problem/motivation
For any configuration that is shipped with Drupal core, they will be shipped in English. It is possible that a foreign language site will not use English at all (it is not added in the installer if installing in a foreign language). However, when editing configuration (such as a vocabulary or view), the language selector on the object will only included configured languages. Since eg. shipped views people will not likely want to edit with all text values manually to be in their own language, we need to support keeping English as an option on the language selector. If we don't, then editing a shipped vocabulary for example would flip it to a different language and translations would not be well aligned anymore.
Proposal
Figure out under what conditions do we need to support English on #type language_select elements. Make sure we do.