Not helped by the fact that even with explicit cajoling* to give steps to reproduce, the reporter wrote:
> Steps to reproduce
>Try to login/create an user in Gitlab (on-premises/Gitlab.com) where the username ends with a MIME type format
Goddamit, those are not steps to reproduce! Has the current era of "social coding" and its terrible software development practices completely turned people's brains to mush?
(In fact, such cajoling shouldn't even be required. If you don't know you need to provide STR without someone going to the lengths of coddling you by going out of their way to create a template, you don't have any business using a bug tracker.)