Regarding Ubuntu 13.04: In addition to working properly with the Ubuntu 3.8.0-7-generic kernel, mirroring also works properly in Ubuntu 13.04 with the mainline 3.8.0 kernel. However, at least for me, mirroring does NOT work properly in Ubuntu 13.04 with the mainline 3.8.1 kernel or with the mainline 3.8.2 kernel. (I haven't yet tried later mainline kernels.)
Regarding Ubuntu 13.04: In addition to working properly with the Ubuntu 3.8.0-7-generic kernel, mirroring also works properly in Ubuntu 13.04 with the mainline 3.8.0 kernel. However, at least for me, mirroring does NOT work properly in Ubuntu 13.04 with the mainline 3.8.1 kernel or with the mainline 3.8.2 kernel. (I haven't yet tried later mainline kernels.)