#25932 introduced code of the form

try:
    vertices = tuple(sorted(vertex_set))
except TypeError:
    vertices = tuple(sorted(vertex_set, key=str))

The problem here is that sorting is not predictable: adding a vertex or considering a face containing only sortable vertices could suddenly change the ordering.

Instead, the sorting key should be explicitly given and the same key should always be used for the same simplicial complex.

CC: @jhpalmieri

Component: python3

Author: Jeroen Demeyer

Branch: 154b615

Reviewer: John Palmieri

Issue created by migration from https://trac.sagemath.org/ticket/26931