package-autoremove and package-directory-list

[Yuri D'Elia]

I have some elisp packages that I manage manually, so I simply put the
directory containing them into 'package-directory-list.

When doing list-packages, they show up as "external".
No problems here.

However, today I tried to run package-autoremove and it seems to be
willing to autoremove external packages as well.

Somehow I'd improve 'package--removable-packages to consider system and
external packages as "needed". You clearly cannot remove a system
package as a regular user, and it's likely to be the same for external
packages.