MAC-Address Thing Rename Bug?

I have added a Netatmo Thing.
Now I want to rename it but I can’t because as of the gui the MAC address is wrong.

It seems the address gets checked against all “digits”, but it has also letters.

Should I report this to any issue tracker?
Does such exists?

Worth a try with uppercase leeters?

Just tried it. If I change the filed I get the error message “Field is required”.
Where should I report this bug?