It seems the latest versions of libappindicator do not allow an indicator to have no icon - previously we could set a NULL icon and that would show no icon, now instead when we do the same the no-icon icon is shown. Perhaps file a bug report against libappindicator due to this change in behaviour? In the meantime I will experiment to see if this can be worked around somehow in indicator-sensors directly.
It seems the latest versions of libappindicator do not allow an indicator to have no icon - previously we could set a NULL icon and that would show no icon, now instead when we do the same the no-icon icon is shown. Perhaps file a bug report against libappindicator due to this change in behaviour? In the meantime I will experiment to see if this can be worked around somehow in indicator-sensors directly.