81cf923fe3
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