dont exit on a missing server
dont exit on a missing server

This errors if a server gets deleted between when the server_list and
show_server commands are run.  When running map files to build servers, this
could cause the entire map to be evaluated as needing to be run.

If a server disappears, just continue and don't include it.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt