Unlike most versioning helper functions, version_mesh_crease_generic
takes care of all meshes in the blend file. However, the versioning
code was looping over all meshes and calling it for each one anyways.
This doesn't do anything after the first iteration, but it results
in quadratic time complexity w.r.t. number of meshes and manages to
waste e.g. 600ms when loading the Spring benchmark file.
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