For Hive tables, the current "replace the schema" code is the correct
path, except that an exception in that path should result in an error, and
not in retrying in a different way.
For data source tables, Spark may generate a non-compatible Hive table;
but for that to work with Hive 2.1, the detection of data source tables needs
to be fixed in the Hive client, to also consider the raw tables used by code
such as `alterTableSchema`.
Tested with existing and added unit tests (plus internal tests with a 2.1 metastore).
Author: Marcelo Vanzin <vanzin@cloudera.com>
Closes#18849 from vanzin/SPARK-21617.
84b5b16ea6