fix hash of multivariate Laurent polynomials

[videlec]

sage: L.<x,y> = LaurentPolynomialRing(QQ)
sage: hash(L.one())  # this is wrong !
3
sage: hash(L.zero()) # this is even worse!
Traceback (most recent call last):
...
AttributeError: 'NoneType' object has no attribute 'is_constant'

Component: algebra

Keywords: thursdaysbdx

Author: Vincent Delecroix

Branch/Commit: 932ccc1

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/23864

[videlec]

Commit: 378d286

[videlec]

Branch: u/vdelecroix/23864

[videlec]

New commits:

378d286

23864: fix hash of multivariate laurent polys

[tscrim]

comment:2

Trivial thing: could you make this doctest consistent with spacing:

hash(1 - 7* x0 + x1*x2) == hash(L(1 - 7 *x0 + x1*x2))

Once done, you can set a positive review on my behalf.

[tscrim]

Reviewer: Travis Scrimshaw

[sagetrac-git]

Changed commit from 378d286 to 932ccc1

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

932ccc1

23864: consistent spacing in doc

[videlec]

comment:4

done! Thanks Travis.

[vbraun]

Changed branch from u/vdelecroix/23864 to 932ccc1