The sage-env script has never been particularly useful in distributions, and has actually been more of a nuisance: it needs to be heavily patched or even replaced with a custom one.

After #25786 (which removes SAGE_DOC_SRC usage at runtime) the only use for it that I can think of is setting DOT_SAGE. This patch allows to completely do away with this script, by setting a fallback for DOT_SAGE in the sage executable.

Depends on #25786

CC: @saraedum @isuruf @kiwifb @timokau

Component: distribution

Author: Antonio Rojas

Branch/Commit: u/arojas/allow_sage_to_run_in_the_absence_of_sage_env @ 83a6cec

Reviewer: François Bissey

Issue created by migration from https://trac.sagemath.org/ticket/28225