Fix #141735: "Join as Shapes" operator too restrictive

Caused by 3d6ea7c075
Before that commit, it was possible to retrieve shape key data from
other objects with a different number of edges or faces. One crucial
case where that is important is when the other mesh is a triangulated
with otherwise the same vertex count.

In general it's better to be flexible and allow other changes besides
the vertex count, especially since that's such a simple check that users
can easily understand.

Pull Request: https://projects.blender.org/blender/blender/pulls/141794

source/blender/editors/mesh/meshtools.cc

@@ -733,7 +733,7 @@ wmOperatorStatus ED_mesh_shapes_join_objects_exec(bContext *C,
   };
 
   auto topology_count_matches = [](const Mesh &a, const Mesh &b) {
-    return a.verts_num == b.verts_num && a.edges_num == b.edges_num && a.faces_num == b.faces_num;
+    return a.verts_num == b.verts_num;
   };
 
   bool found_object = false;
@@ -773,9 +773,7 @@ wmOperatorStatus ED_mesh_shapes_join_objects_exec(bContext *C,
   }
 
   if (found_non_equal_count) {
-    BKE_report(reports,
-               RPT_WARNING,
-               "Selected meshes must have equal numbers of vertices, edges, and faces");
+    BKE_report(reports, RPT_WARNING, "Selected meshes must have equal numbers of vertices");
     return OPERATOR_CANCELLED;
   }