when a single language vocabulary is converted to a language neutral vocabulary, terms stay in original language

i had a vocabulary that was set to english. i needed to change it to language neutral so i could localize the terms. after setting the vocabulary language to neutral (blank), my terms would not show up for nodes of any language aside from english. after inspecting the db table (term_data), i noticed my terms for my language neutral vocabulary were still set to en. i reset them all to blank manually, and now all the terms show up in the other languages, get properly localized, etc.

steps to recreate:

1) create a vocabulary with translation mode: none. language: english.
2) add terms for the vocabulary.
3) change vocabulary to translation mode: localize terms
4) change vocabulary language to none (blank)
5) create a node in a non-english language. the dropdown for the taxonomy terms will be blank.

to fix:

1) with phpmyadmin (or tool of your choice) browse db table term_data.
2) for all terms in your new vocabulary, you will see they are all still set to english.
3) manually set the language field to nothing (blank)
4) create a node in a non-english language. the dropdown for the taxonomy terms will be correct.

expected functionality: converting a vocabulary from a language to no language should automatically convert all the terms back to language neutral (or at least an option/prompt should be provided to do so).