Because after the install most people will have taken the CD-Rom out of the tray and you receive an error message that it is not available. Maybe Bug is the wrong choice of wording. Perhaps it Could/Would/Should be viewed as a bad default to leave it selected ?
zebedee@i7-ubuntu-budgie:~$ sudo apt update
Ign:1 cdrom://Ubuntu-Budgie 19.04 _Disco Dingo_ - Alpha amd64 (20190403) disco InRelease
Err:2 cdrom://Ubuntu-Budgie 19.04 _Disco Dingo_ - Alpha amd64 (20190403) disco Release
Please use apt-cdrom to allow APT to recognise this CD-ROM. 'apt-get update' cannot be used to add new CD-ROMs
Hit:3 http://security.ubuntu.com/ubuntu disco-security InRelease
Hit:4 http://gb.archive.ubuntu.com/ubuntu disco InRelease
Hit:5 http://gb.archive.ubuntu.com/ubuntu disco-updates InRelease
Hit:6 http://gb.archive.ubuntu.com/ubuntu disco-backports InRelease
Reading package lists... Done
E: The repository 'cdrom://Ubuntu-Budgie 19.04 _Disco Dingo_ - Alpha amd64 (20190403) disco Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
zebedee@i7-ubuntu-budgie:~$
Because after the install most people will have taken the CD-Rom out of the tray and you receive an error message that it is not available. Maybe Bug is the wrong choice of wording. Perhaps it Could/Would/Should be viewed as a bad default to leave it selected ?
zebedee@ i7-ubuntu- budgie: ~$ sudo apt update /Ubuntu- Budgie 19.04 _Disco Dingo_ - Alpha amd64 (20190403) disco InRelease /Ubuntu- Budgie 19.04 _Disco Dingo_ - Alpha amd64 (20190403) disco Release security. ubuntu. com/ubuntu disco-security InRelease gb.archive. ubuntu. com/ubuntu disco InRelease gb.archive. ubuntu. com/ubuntu disco-updates InRelease gb.archive. ubuntu. com/ubuntu disco-backports InRelease //Ubuntu- Budgie 19.04 _Disco Dingo_ - Alpha amd64 (20190403) disco Release' does not have a Release file. i7-ubuntu- budgie: ~$
Ign:1 cdrom:/
Err:2 cdrom:/
Please use apt-cdrom to allow APT to recognise this CD-ROM. 'apt-get update' cannot be used to add new CD-ROMs
Hit:3 http://
Hit:4 http://
Hit:5 http://
Hit:6 http://
Reading package lists... Done
E: The repository 'cdrom:
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
zebedee@