Filter singular system package out of tox.ini for homebrew

[orlitzky]

As a follow-up to #29024, we prevent the system singular from being used to run GH actions when the homebrew prefix is not /usr/local (which causes problems for its singular package).

CC: @mkoeppe @dimpase

Component: build

Branch/Commit: u/mjo/ticket/32784 @ e4aa49e

Reviewer: Michael Orlitzky

Issue created by migration from https://trac.sagemath.org/ticket/32784

[orlitzky]

comment:1

Untested, needs a run on GH obviously...

---

New commits:

030ec23

Trac #32784: filter singular in tox.ini for homebrew.

[orlitzky]

Commit: 030ec23

[orlitzky]

Branch: u/mjo/ticket/32784

[orlitzky]

Author: Michael Orlitzky

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

e4aa49e

Trac #32784: filter singular in tox.ini for homebrew.

[sagetrac-git]

Changed commit from 030ec23 to e4aa49e

[mkoeppe]

comment:3

Turns out this patch is not needed for our GH Actions.

Homebrew's from-source installation of singular only fails if there's already a homebrew-installed flint in /usr/local (or any of the paths of Singular's DEFAULT_CHECKING_PATH.

[mkoeppe]

comment:4

Homebrew does not like people to report bugs with the from-source installation, so perhaps instead we should send them a PR that adds flint as a dependency to https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/singular.rb