After rebooting and autoremoving the 2nd oldest kernel the /etc/apt/apt.conf.d/01autoremove-kernels file reverts to listing the 3.19.0-11-generic and 3.19.0-12-generic kernels. So only one kernel, the latest 3.19.0-12-generic is left.
After rebooting and autoremoving the 2nd oldest kernel the /etc/apt/ apt.conf. d/01autoremove- kernels file reverts to listing the 3.19.0-11-generic and 3.19.0-12-generic kernels. So only one kernel, the latest 3.19.0-12-generic is left.