Comment 26 for bug 1309025

Following from the errors.ubuntu.com link, and looking at the thread stack
trace there, it has

#3 0xb7694d63 in cgmanager_set_value_scm_sync (parent=0x0, proxy=0x0, controller=0x8071f35 "systemd", cgroup=0x868b579 "user/140.user/c2.session", key=0x807d84e "tasks", value=0xbfa6b5ec "", sockfd=68) at cgmanager-client.c:4320
        method_call = 0x1
        iter = {dummy1 = 0xb7683004 <__nih_free>, dummy2 = 0xb766f1cf <nih_free+623>, dummy3 = 0, dummy4 = -1079593560, dummy5 = 6897520, dummy6 = -1751146240, dummy7 = -1219624852, dummy8 = 0, dummy9 = -1, dummy10 = 134769652, dummy11 = 1, pad1 = 141098216, pad2 = 141098208, pad3 = 0x0}
        error = {name = 0xbfa6b58c "\364k\b\b\001", message = 0xb7682e58 "H}\001", dummy1 = 0, dummy2 = 0, dummy3 = 0, dummy4 = 1, dummy5 = 0, padding1 = 0x868fce8}
        reply = <optimized out>
        __FUNCTION__ = "cgmanager_set_value_scm_sync"
#4 0x0806cdfa in cgm_get (controller=0x8071f35 "systemd", cgroup_path=0x868b579 "user/140.user/c2.session", cgroup_path@entry=0x868b578 "/user/140.user/c2.session", key=key@entry=0x807d84e "tasks") at ../src/shared/cgmanager.c:135
        result = 0x0
        __func__ = "cgm_get"

which is confusing since cgm_get calls cgmanager_get_value_scm_sync, not
cgmanager_set_value_scm_sync. Which suggests memory corruption - which
could of course be happening anywhere.

I've tried this before, but will (on tuesday) set up an attempt to
reproduce with a great number of repeated logins.