https://bugzilla.redhat.com/show_bug.cgi?id=684655 points out
a regression introduced in commit 2215050e - non-root users
can't connect to qemu:///session because libvirtd dies when
it can't use pciaccess initialization.

* src/node_device/node_device_udev.c (udevDeviceMonitorStartup):
Don't abort udev driver (and libvirtd overall) if non-root user
can't use pciaccess.