Text generating index object names containing "[" for indexes on partitioned tables

We have a table in 11.2.0.2 with over 11,000 partitions with a local CONTEXT index on it.  We also have Oracle Label Security installed, but there is no policy enabled.  Occasionally, we've had index partition rebuilds fail when OLS trips over a table_name like "OWNER"."DR#INDEX_NAME_AAA[$I" during a DBMS_ASSERT.SIMPLE_SQL_NAME check.  The "[" in the object name seems to be the offending character.  I found what seems to be the Text function that generates these object names: CTXSYS.DRIUTL.MAKE_PFX.  Given the appropriate partition numbers, the function generates name prefixes with the "[" in them for certain partitions.  The function uses the letters A-Z,