make xz a standard package

[EmmanuelCharpentier]

Rationale :

• R is a standard package.
• It now depends on liblzma (see Upgrade R to 3.3.3 #20523).
• liblzma is available through xz.
• Therefore R depends on xz.
• A standard package cannot depend on an optional package

Therefore xz has to become standard. QED.

Trivial patch to follow shortly (Real_World(TM) adjuvante)...

Component: packages: optional

Author: Emmanuel Charpentier

Branch/Commit: b4da321

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/21744

[EmmanuelCharpentier]

Branch: u/charpent/make_zx_a_standard_package

[EmmanuelCharpentier]

comment:3

Passes ptestlong with two transient errors, as usual :

----------------------------------------------------------------------
sage -t --long --warn-long 99.8 src/sage/homology/simplicial_complex.py  # 1 doctest failed
sage -t --long --warn-long 99.8 src/sage/categories/sets_cat.py  # Bad exit: 2
----------------------------------------------------------------------

which both pâss standalone with no error.

==> needs_review

---

New commits:

b4da321

One-word patch.

[EmmanuelCharpentier]

Author: Emmanuel Charpentier

[EmmanuelCharpentier]

Commit: b4da321

[EmmanuelCharpentier]

comment:4

Replying to @mkoeppe:

Thanks ! I'm a bit of a distracted man...

[tscrim]

comment:5

A notice about this should be posted to sage-devel, but I am in favor of this change.

[EmmanuelCharpentier]

comment:6

Replying to @tscrim:

A notice about this should be posted to sage-devel, but I am in favor of this change.

Done here. Thanks for the reminder...

[mkoeppe]

comment:7

The outcome of the poll on sage-devel seems to have been positive, so I'm setting this to positive review.
(I'd like to use xz for a CGAL package, #18197.)

[mkoeppe]

Reviewer: Matthias Koeppe

[vbraun]

Changed branch from u/charpent/make_zx_a_standard_package to b4da321