dbcase.js and dbcase2.js pass if run directly without mongos using write commands. It looks like there is a different in the formatting of the returned object:

direct to mongod:

{ "errmsg" : "exception: db already exists with different case other: [dbcasetest_dbnamea] me [dbcasetest_dbnameA]", "code" : 13297, "ok" : 0 }

through mongos:

{ "$err" : "error creating initial database config information :: caused by :: can't have 2 databases that just differ on case have: dbcasetest_dbnamea want to add: dbcasetest_dbnameA", "code" : 13297 }