doctest previous is_polynomial() wrong results

[defeo]

It is not the first time is_polynomial() behaves wrong, see #11352.

Here's the bug:

sage: var('x,y')
(x, y)
sage: (y/x).is_polynomial(x)
True

Component: symbolics

Keywords: polynomial symbolic

Author: Ralf Stephan

Branch/Commit: 7777342

Reviewer: Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/15304

[rwst]

Branch: u/rws/is_polynomial___returns_wrong_results

[rwst]

comment:5

This is no longer an issue. So we just add a doctest.

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New commits:

7777342

15304: doctest

[rwst]

Author: Ralf Stephan

[rwst]

Commit: 7777342