VDS roundtrip to dms fails.

OpenVDS #9d3e767e I did the following (partly redacted)

• VDSCopy Volve_from_segy.vds sd://tenant/project/tmp.vds
• VDSCopy sd://tenant/project/tmp.vds roundtrip.vds

The second line resulted in an error about "TraceDimensions_012LOD0/ChunkMetadata/0" not being found.