TST: Access mds exceptions only through attriburtes so that tests are portable.
TST: Access mds exceptions only through attriburtes so that tests are portable.

tacaswell/metadataStore,ericdill/databroker,arkilic/metadatastore,NSLS-II/metadatastore,hhslepicka/metadatastore,NSLS-II/metadatastore,tacaswell/metadataStore,ericdill/databroker,hhslepicka/metadatastore,arkilic/metadatastore