I suppose the user container runs upstart (from the template), as that's still the ubuntu vivid default. But I have a feeling it's not even getting that far; when I start with --logfile /dev/stdout --logpriority debug it all just seems to be early setup:

$ lxc-start -n v1 --logfile /dev/stdout --logpriority debug  -F 
      lxc-start 1422005786.443 INFO     lxc_start_ui - lxc_start.c:main:265 - using rcfile /home/martin/.local/share/lxc/v1/config
      lxc-start 1422005786.444 WARN     lxc_confile - confile.c:config_pivotdir:1776 - lxc.pivotdir is ignored.  It will soon become an error.
      lxc-start 1422005786.445 INFO     lxc_confile - confile.c:config_idmap:1384 - read uid map: type u nsid 0 hostid 100000 range 65536
      lxc-start 1422005786.445 INFO     lxc_confile - confile.c:config_idmap:1384 - read uid map: type g nsid 0 hostid 100000 range 65536
      lxc-start 1422005786.445 WARN     lxc_log - log.c:lxc_log_init:316 - lxc_log_init called with log already initialized
      lxc-start 1422005786.446 WARN     lxc_cgmanager - cgmanager.c:cgm_get:963 - do_cgm_get exited with error
      lxc-start 1422005786.447 INFO     lxc_lsm - lsm/lsm.c:lsm_init:48 - LSM security driver AppArmor
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:298 - processing: .reject_force_umount  # comment this to allow umount -f;  not recommended.
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:371 - Adding non-compat rule for reject_force_umount action 0
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:do_resolve_add_rule:192 - Setting seccomp rule to reject force umounts

      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:382 - Adding compat rule for reject_force_umount action 0
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:390 - Adding non-compat rule bc nr1 == nr2 (-1, -1)
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:do_resolve_add_rule:192 - Setting seccomp rule to reject force umounts

      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:298 - processing: .[all].
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:298 - processing: .kexec_load errno 1.
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:371 - Adding non-compat rule for kexec_load action 327681
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:382 - Adding compat rule for kexec_load action 327681
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:395 - Really adding compat rule bc nr1 == nr2 (283, 246)
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:298 - processing: .open_by_handle_at errno 1.
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:371 - Adding non-compat rule for open_by_handle_at action 327681
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:382 - Adding compat rule for open_by_handle_at action 327681
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:395 - Really adding compat rule bc nr1 == nr2 (342, 304)
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:298 - processing: .init_module errno 1.
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:371 - Adding non-compat rule for init_module action 327681
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:382 - Adding compat rule for init_module action 327681
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:395 - Really adding compat rule bc nr1 == nr2 (128, 175)
      lxc-start 1422005786.447 INFO     lxc_seccomp - seccomp.c:parse_config_v2:298 - processing: .finit_module errno 1.
      lxc-start 1422005786.448 INFO     lxc_seccomp - seccomp.c:parse_config_v2:371 - Adding non-compat rule for finit_module action 327681
      lxc-start 1422005786.448 WARN     lxc_seccomp - seccomp.c:do_resolve_add_rule:209 - Seccomp: got negative # for syscall: finit_module
      lxc-start 1422005786.448 WARN     lxc_seccomp - seccomp.c:do_resolve_add_rule:210 - This syscall will NOT be blacklisted
      lxc-start 1422005786.448 INFO     lxc_seccomp - seccomp.c:parse_config_v2:382 - Adding compat rule for finit_module action 327681
      lxc-start 1422005786.448 INFO     lxc_seccomp - seccomp.c:parse_config_v2:390 - Adding non-compat rule bc nr1 == nr2 (-10085, -10085)
      lxc-start 1422005786.448 WARN     lxc_seccomp - seccomp.c:do_resolve_add_rule:209 - Seccomp: got negative # for syscall: finit_module
      lxc-start 1422005786.448 WARN     lxc_seccomp - seccomp.c:do_resolve_add_rule:210 - This syscall will NOT be blacklisted
      lxc-start 1422005786.448 INFO     lxc_seccomp - seccomp.c:parse_config_v2:298 - processing: .delete_module errno 1.
      lxc-start 1422005786.448 INFO     lxc_seccomp - seccomp.c:parse_config_v2:371 - Adding non-compat rule for delete_module action 327681
      lxc-start 1422005786.448 INFO     lxc_seccomp - seccomp.c:parse_config_v2:382 - Adding compat rule for delete_module action 327681
      lxc-start 1422005786.448 INFO     lxc_seccomp - seccomp.c:parse_config_v2:395 - Really adding compat rule bc nr1 == nr2 (129, 176)
      lxc-start 1422005786.448 INFO     lxc_seccomp - seccomp.c:parse_config_v2:403 - Merging in the compat seccomp ctx into the main one
      lxc-start 1422005786.449 DEBUG    lxc_conf - conf.c:lxc_create_tty:3299 - allocated pty '/dev/pts/23' (5/6)
      lxc-start 1422005786.449 DEBUG    lxc_conf - conf.c:lxc_create_tty:3299 - allocated pty '/dev/pts/24' (7/8)
      lxc-start 1422005786.449 DEBUG    lxc_conf - conf.c:lxc_create_tty:3299 - allocated pty '/dev/pts/25' (9/10)
      lxc-start 1422005786.449 DEBUG    lxc_conf - conf.c:lxc_create_tty:3299 - allocated pty '/dev/pts/26' (11/12)
      lxc-start 1422005786.449 INFO     lxc_conf - conf.c:lxc_create_tty:3310 - tty's configured
      lxc-start 1422005786.449 DEBUG    lxc_start - start.c:setup_signal_fd:259 - sigchild handler set
      lxc-start 1422005786.449 DEBUG    lxc_console - console.c:lxc_console_peer_default:500 - opening /dev/tty for console peer
      lxc-start 1422005786.449 INFO     lxc_caps - caps.c:lxc_caps_up:101 - Last supported cap was 36
      lxc-start 1422005786.449 DEBUG    lxc_console - console.c:lxc_console_peer_default:506 - using '/dev/tty' as console
      lxc-start 1422005786.449 DEBUG    lxc_console - console.c:lxc_console_sigwinch_init:179 - 16011 got SIGWINCH fd 17
      lxc-start 1422005786.449 DEBUG    lxc_console - console.c:lxc_console_winsz:88 - set winsz dstfd:14 cols:90 rows:34
      lxc-start 1422005786.677 INFO     lxc_start - start.c:lxc_init:455 - 'v1' is initialized
      lxc-start 1422005786.677 DEBUG    lxc_start - start.c:__lxc_start:1072 - Not dropping cap_sys_boot or watching utmp
      lxc-start 1422005786.677 INFO     lxc_start - start.c:lxc_spawn:816 - Cloning a new user namespace
      lxc-start 1422005786.677 INFO     lxc_cgroup - cgroup.c:cgroup_init:65 - cgroup driver cgmanager initing for v1
      lxc-start 1422005786.686 ERROR    lxc_cgmanager - cgmanager.c:lxc_cgmanager_enter:694 - call to cgmanager_move_pid_sync failed: invalid request
lxc-start: cgmanager.c: lxc_cgmanager_enter: 694 call to cgmanager_move_pid_sync failed: invalid request
      lxc-start 1422005786.720 ERROR    lxc_start - start.c:__lxc_start:1099 - failed to spawn 'v1'
lxc-start: start.c: __lxc_start: 1099 failed to spawn 'v1'
      lxc-start 1422005786.724 ERROR    lxc_start_ui - lxc_start.c:main:345 - The container failed to start.
lxc-start: lxc_start.c: main: 345 The container failed to start.
      lxc-start 1422005786.724 ERROR    lxc_start_ui - lxc_start.c:main:349 - Additional information can be obtained by setting the --logfile and --logpriority options.
lxc-start: lxc_start.c: main: 349 Additional information can be obtained by setting the --logfile and --logpriority options.