ATLAS spkg doesn't need /Sage's/ python to build

[nexttime]

Since we meanwhile require a system python to let Sage build anyway, we don't have to wait with building ATLAS until Sage's python has been built, as ATLAS doesn't install any Python libraries, but only its spkg-install has been rewritten in Python quite a while ago.

This requires two things:

• Remove the dependency of ATLAS on $(PYTHON) (which means Sage's python2 or python3 package) in its dependencies.

• Make ATLAS' spkg-install again a shell script, renaming the current one to spkg-install.py, say, where the shell script just contains

#!/bin/sh
exec python spkg-install.py

This is necessary because sage-spkg checks whether Sage's python is already installed if an spkg-install script starts with #! ... python, and bails out otherwise:

atlas-3.10.2.p2
====================================================
Setting up build directory for atlas-3.10.2.p2
Finished set up
Error: The spkg-install script is written in Python, but the Python
package is not yet installed in Sage.  You should add $(PYTHON)
as dependency in build/pkgs/atlas/dependencies
make[2]: *** [.../sage/local/var/lib/sage/installed/atlas-3.10.2.p2] Error 1

(Note that this message originates from a build where the Makefile was broken, such that the make dependency of ATLAS on the python package was fulfilled by $(PYTHON) accidentally being empty. So one won't get this message unless the Makefile is corrupted.)

---

Rather orthogonal to that, our top-level configure doesn't contain any check for python yet, although currently at least sage-download-file and sage-uncompress-spkg require (a system) python (in the beginning of the build). I'll address that on another ticket -- see #21116.

Depends on #30350

CC: @vbraun

Component: packages: standard

Keywords: sage-spkg dependencies spkg-install

Reviewer: Michael Orlitzky

Issue created by migration from https://trac.sagemath.org/ticket/21114

[mkoeppe]

comment:2

outdated after atlas spkg removal in #30350

[mkoeppe]

Dependencies: #30350

[orlitzky]

Reviewer: Michael Orlitzky