Custom Block References containing capital letters fail and fall back to whole page matches

When defining a custom block reference ^<string> if the string contains capital letters than block matching fails. It falls back to matching the whole page

Can easily reproduced by adding ^test and ^TEST to two different blocks. the embed logic will then fail.

This is not really a bug. BlockIDs are not case sensitive. So ^TEST, ^test, ^TeSt are all the same. We will add this to the docs.

In the future, follow the bug report template.