Just discovered this bug, and I cant seem to find it reported.
To reproduce: Create a flow with one group that starts with a second participant/actor (or even more to the left), and then create a nested group within that one. With teoz, the parent group will be drawn extending all the way to the left.
Without teoz, the parent group is drawn as expected. Without the nested group, teoz draws the parent correctly.
Link to this diagram.
( http://www.plantuml.com/plantuml/uml/LP2zZi8m381tFuNHIRSL2GfBXwfR5uHku0NouqiZqIPANGbuUbnQeMQAF-Vx5ZSZgyHJVuTTJChr2fd22pbD1D1vI_WV0klm08WYUkEZ6XXLHZeZav7DY01KKUiA3_2BkgXDXKTmAKmHVsv93QF89DxVyhJp3wpUVcvCKTjv_bONxpfk4ptnIYEJNHlxQKffbgAKGdPKuGbeiEWsrdcpQMIKQxm1 )