FTP-Username keeps no prefix if suffix is only a number
short description
When users edit ftp-usernames they can change the complete name (including the prefix), when the suffix contains only numbers.
correct behaviour
We use "[CLIENTNAME]ftp" as FTP-User-Prefix, and when users edit the ftp-users they should only be able to change the suffix, not the complete name.
environment
Server OS: debian Server OS version: stretch ISPConfig version: 3.1.13