This is a shell bug and it's not a new one. Basically the mongo shell doesn't accept the same format of connection string that regular mongodb drivers do. I can reproduce this error in the current and previous versions and this syntax isn't expected to work (though it probably shouldn't crash either, but there is already a bug for the shell to accept standard connection string: jira.mongodb.org/browse/SERVER-3254
Meanwhile you can connect by using the mongo shell options such as
mongo -u <user> -p <passwd> hostIP:port/db
or
mongo --host host --port port [ other options ] db