gh-38940: Fix flaky simplicial set test

    
Fixes #38888 .

This test has been failing sporadically recently e.g. https://github.com
/sagemath/sage/actions/runs/11733902583/job/32689016794?pr=38938 .

From my understanding of simplicial set, the two `sigma_1` are actually
representing two different cells (the wedge looks like a "8" shape), but
because they both come from `S1` (the 1-sphere i.e. circle), they get
the same name.

SageMath does some magic during doctest so that dict entries are sorted,
but the problem is

```
        At this point, comparison between v and w is random, based on
        their location in memory. ::
```

so with some chance it fails.

This change should make it deterministic --- since the two faces are
named `sigma_1` and `sigma_1'`, the comparison should be by custom
name…?

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [x] I have created tests covering the changes. (not applicable)
- [x] I have updated the documentation and checked the documentation
preview.
    
URL: #38940
Reported by: user202729
Reviewer(s): Tobias Diez

src/sage/categories/simplicial_sets.py

@@ -444,29 +444,31 @@ def covering_map(self, character):
 
                     sage: # needs sage.graphs sage.groups
                     sage: S1 = simplicial_sets.Sphere(1)
-                    sage: W = S1.wedge(S1)
+                    sage: S1_ = simplicial_sets.Sphere(1)
+                    sage: S1_.n_cells(1)[0].rename("sigma_1'")
+                    sage: W = S1.wedge(S1_)
                     sage: G = CyclicPermutationGroup(3)
                     sage: a, b = W.n_cells(1)
                     sage: C = W.covering_map({a : G.gen(0), b : G.one()}); C
                     Simplicial set morphism:
                       From: Simplicial set with 9 non-degenerate simplices
                       To:   Wedge: (S^1 v S^1)
-                      Defn: [(*, ()), (*, (1,2,3)), (*, (1,3,2)), (sigma_1, ()),
-                             (sigma_1, ()), (sigma_1, (1,2,3)), (sigma_1, (1,2,3)),
-                             (sigma_1, (1,3,2)), (sigma_1, (1,3,2))]
-                            --> [*, *, *, sigma_1, sigma_1, sigma_1, sigma_1, sigma_1, sigma_1]
+                      Defn: [(*, ()), (*, (1,2,3)), (*, (1,3,2)), (sigma_1', ()),
+                             (sigma_1', (1,2,3)), (sigma_1', (1,3,2)), (sigma_1, ()),
+                             (sigma_1, (1,2,3)), (sigma_1, (1,3,2))]
+                            --> [*, *, *, sigma_1', sigma_1', sigma_1', sigma_1, sigma_1, sigma_1]
                     sage: C.domain()
                     Simplicial set with 9 non-degenerate simplices
                     sage: C.domain().face_data()
                     {(*, ()): None,
                      (*, (1,2,3)): None,
                      (*, (1,3,2)): None,
+                     (sigma_1', ()): ((*, ()), (*, ())),
+                     (sigma_1', (1,2,3)): ((*, (1,2,3)), (*, (1,2,3))),
+                     (sigma_1', (1,3,2)): ((*, (1,3,2)), (*, (1,3,2))),
                      (sigma_1, ()): ((*, (1,2,3)), (*, ())),
-                     (sigma_1, ()): ((*, ()), (*, ())),
                      (sigma_1, (1,2,3)): ((*, (1,3,2)), (*, (1,2,3))),
-                     (sigma_1, (1,2,3)): ((*, (1,2,3)), (*, (1,2,3))),
-                     (sigma_1, (1,3,2)): ((*, ()), (*, (1,3,2))),
-                     (sigma_1, (1,3,2)): ((*, (1,3,2)), (*, (1,3,2)))}
+                     (sigma_1, (1,3,2)): ((*, ()), (*, (1,3,2)))}
                 """
                 from sage.topology.simplicial_set import AbstractSimplex, SimplicialSet
                 from sage.topology.simplicial_set_morphism import SimplicialSetMorphism
@@ -530,20 +532,22 @@ def cover(self, character):
 
                     sage: # needs sage.graphs sage.groups
                     sage: S1 = simplicial_sets.Sphere(1)
-                    sage: W = S1.wedge(S1)
+                    sage: S1_ = simplicial_sets.Sphere(1)
+                    sage: S1_.n_cells(1)[0].rename("sigma_1'")
+                    sage: W = S1.wedge(S1_)
                     sage: G = CyclicPermutationGroup(3)
                     sage: (a, b) = W.n_cells(1)
                     sage: C = W.cover({a : G.gen(0), b : G.gen(0)^2})
                     sage: C.face_data()
                     {(*, ()): None,
                      (*, (1,2,3)): None,
                      (*, (1,3,2)): None,
+                     (sigma_1', ()): ((*, (1,3,2)), (*, ())),
+                     (sigma_1', (1,2,3)): ((*, ()), (*, (1,2,3))),
+                     (sigma_1', (1,3,2)): ((*, (1,2,3)), (*, (1,3,2))),
                      (sigma_1, ()): ((*, (1,2,3)), (*, ())),
-                     (sigma_1, ()): ((*, (1,3,2)), (*, ())),
                      (sigma_1, (1,2,3)): ((*, (1,3,2)), (*, (1,2,3))),
-                     (sigma_1, (1,2,3)): ((*, ()), (*, (1,2,3))),
-                     (sigma_1, (1,3,2)): ((*, ()), (*, (1,3,2))),
-                     (sigma_1, (1,3,2)): ((*, (1,2,3)), (*, (1,3,2)))}
+                     (sigma_1, (1,3,2)): ((*, ()), (*, (1,3,2)))}
                     sage: C.homology(1)                                                 # needs sage.modules
                     Z x Z x Z x Z
                     sage: C.fundamental_group()