Ticket #19004 has the very user-unfriendly consequence that all old-style packages are effectively gone:

$ ./sage -i chomp
Attempting to download package chomp
Error: could not find a package matching chomp
       Try 'sage --package list' to see the available packages
       Did you mean: csdp, gmp, cbc, cmake, cvxopt?

Instead of removing support for old-style packages, we should deprecate them.

Depends on #19101

CC: @nathanncohen @vbraun @jhpalmieri

Component: scripts

Author: Jeroen Demeyer

Branch/Commit: 3dda704

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/19158