Geo3d test failure

Reproducible on master with:

ant test  -Dtestcase=TestGeo3DPoint -Dtests.method=testGeo3DRelations -Dtests.seed=EEA08DD7FAE3C688 -Dtests.multiplier=2 -Dtests.slow=true -Dtests.directory=MMapDirectory -Dtests.locale=es -Dtests.timezone=America/Manaus -Dtests.asserts=true -Dtests.file.encoding=UTF-8

Note: I was initially unable to reproduce this, until I pulled up code that mikemccand recently committed. It seems possible that encoding/decoding changes are triggering it. Of specific concern is the new way maximum/minimum decoded values are computed.