Up/down vote for tags that contains uppercase letters updates a lowercase version of that tag

New tags are created with lowercase letters, but some tags still contain capital letters (database inconsistencies?)
When you up-down vote such a tag that contains capital letters, it updates a lowercase version of that tag.
This is quite confusing, as you would expect your up-down vote to affect the actual tag you selected.

How to reproduce:

Step 1: select an entity that has an a tag with capital letter attached to it. Ex:
http://musicbrainz.org/recording/8562b9bc-b324-4da1-bc17-c321d98713ed/tags

Step2: up/down vote the tag

Step3: wait a few seconds for database update

Step 4: refresh the tag by reloading the page.

Could you change that behavior if tags with uppercase letters are really allowed ?
Or otherwise lowercase all tags in the database?

Thanks