This does an incremental build of Sage on top of a prebuilt image published at ghcr.io (https://github.com/orgs/sagemath/packages?tab=packages)

For example:

$ tox -e docker-fedora-31-standard-incremental

CC: @dimpase @kliem

Component: porting

Author: Matthias Koeppe

Branch/Commit: 85ce9a6

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/34228