Comment 2 for bug 1849130

That's intentional; if the patron doesn't supply a preferred username when they request a card, a UUID will be auto-generated to fill in a value. The workflow assumes that the staff member will assign a "real" username in place of the UUID when confirming the registration. If fact, it forces the matter: if the username looks like a UUID, the username field in the patron registration form is set to blank.

The usrname column is required to have a value in staging.user_stage. A UUID is used (in part) rather than the empty string because the self-registration interface will check if a patron's requested user name matches one already present in the database (and UUIDs are rather unlikely to hit a duplicate).

This behavior is not necessarily set in stone, however. The requested username field could be left blank, but in that case, additional work will be required in the patron registration form, as it currently uses the staged username as the key for retrieving the information when loading a staged patron record into the registration interface.