Explicitly tag copy-on-write form library remap. Previously, this
tag was used implicitly via geometry/transform tagging, which worked
ok for objects. For non-objects we do need to ensure all copies has
correct pointer and the only way to do so is to pass tag explicitly.
There is probably more places in the library remap where this is
needed, but not being familiar with the code makes it difficult to
spot where possible tags are missing.
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