When performing a database save into a directory which has a previous save,
the save process renames the oracle_rman to oracle_rman_prior to preserve
the existing save in the case the new save fails.
Some of the reasons it may be unable to do:
1) There is a file open in the oracle_rman directory
2) The permissions on the oracle_rman directory have changed so it cannot be
renamed by the $NH_USER