The `rabbitmqctl list_users` command will list the user's last login time
which does not include `\t` character. This is causing a ValueError exception
when attempting to split a user and its tags from the command output. This
fix will check for a `\t` in the current line of the output before splitting.
Right now even if you pass in an empty tags list to the module (either with
an empty string or null) it will erroneously think the tags list have changed
and re-apply the tags on every run