Do not use sage-pip-uninstall for PEP-517 packages, do not give up if sage-pip-uninstall fails

[mkoeppe]

sage-pip-uninstall is invoked before installing a Python package to "force-uninstall" an existing installation. This (1) predates the use of the staging install (DESTDIR), which we use for all Python packages; (2) depends on packages supporting setup.py --name.

As a step toward retiring this mechanism, we

• do not call sage-pip-uninstall for PEP-517 packages without setup.py
• make it only a warning if the sage-pip-uninstall script fails.

This is necessary for some upgrades attempted in #31280 and also works around a failure observed on cygwin-standard (likely because setup.py --name printed extra output that the script cannot parse) -https://github.com/mkoeppe/sage/runs/1943937811

  [scipy-1.5.4]   Package 'scipy' is currently not installed
  [scipy-1.5.4]   No legacy uninstaller found for 'scipy'; nothing to do
  [scipy-1.5.4]   Note: CFLAGS, CXXFLAGS and SHAREDFLAGS are taken from distutils,
  [scipy-1.5.4]         so their current settings are ignored.
  [scipy-1.5.4]   Installing scipy-1.5.4
  [scipy-1.5.4]   Error: could not determine package name
  [scipy-1.5.4]   ********************************************************************************
  [scipy-1.5.4]   Error uninstalling a previous version of scipy-1.5.4
  [scipy-1.5.4]   ********************************************************************************
  [scipy-1.5.4]   
  [scipy-1.5.4]   real	0m2.368s
  [scipy-1.5.4]   user	0m0.590s
  [scipy-1.5.4]   sys	0m0.928s
  [scipy-1.5.4]   ************************************************************************
  [scipy-1.5.4]   Error installing package scipy-1.5.4

CC: @embray @jhpalmieri @dimpase @kliem

Component: build

Author: Matthias Koeppe

Branch/Commit: efe7523

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/31423

[mkoeppe]

Branch: u/mkoeppe/do_not_give_up_if_sage_pip_uninstall_fails

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Commit: 202f99a

[mkoeppe]

New commits:

202f99a

build/bin/sage-dist-helpers (sdh_pip_install): Do not give up if sage-pip-uninstall fails

[mkoeppe]

Reviewer: https://github.com/mkoeppe/sage/actions/runs/606112478

[sagetrac-git]

Changed commit from 202f99a to efe7523

[sagetrac-git]

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

a046780	build/bin/sage-dist-helpers (sdh_pip_install): Do not give up if sage-pip-uninstall fails
efe7523	build/bin/sage-pip-install: For PEP 517 packages, do not try to uninstall first

[mkoeppe]

comment:6

(Commit efe7523 was previously on the branch of #31280.)

[mkoeppe]

comment:8

Again seen in https://github.com/sagemath/sage/runs/2115956504

Let's get this in, please.

[dimpase]

Changed reviewer from https://github.com/mkoeppe/sage/actions/runs/606112478 to Dima Pasechnik

[dimpase]

comment:9

OK, https://github.com/mkoeppe/sage/actions/runs/606112478 looks OK

[mkoeppe]

comment:10

Thank you!

[vbraun]

Changed branch from u/mkoeppe/do_not_give_up_if_sage_pip_uninstall_fails to efe7523