Can not adduser with just number

[Thomas E. Maleshafske]

Was trying to add a user via adduser with just the username of 1600 and the following is displayed:
adduser: Please enter a username matching the regular expression configured
via the NAME_REGEX[_SYSTEM] configuration variable. Use the `--force-badname'
option to relax this check or reconfigure NAME_REGEX.
I checked the options fore the NAME_REGEX in /etc/adduser.conf and it is commented out and shouldn't be affecting the adduser command.

[Ｖ字龍(Vdragon) (vdragon)]

No, NAME_REGEX is or not commented out doesn't mean adduser didn't have a default NAME_REGEX setting, in fact when NAME_REGEX is uncommented it should overwrite adduser's default setting and let the magic work.

[Ｖ字龍(Vdragon) (vdragon)]

And while I didn't meant that it's 100% impossible to create such usernames, it is really not a good practice since programs distinguish username from UID by the first character.

Therefore I'd like to make this bug `invalid`.