toggling bluez adapter's Powered is unreliable

powering down an adapter times out, and powering it back up again doesn't seem to work at all.

Demonstration with bluez-test-adapter after a cold boot:

---

charles@sita:~$ bluez-test-adapter powered
1
charles@sita:~$ bluez-test-adapter powered off
Traceback (most recent call last):
  File "/usr/bin/bluez-test-adapter", line 84, in <module>
    adapter.SetProperty("Powered", value)
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 70, in __call__
    return self._proxy_method(*args, **keywords)
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
charles@sita:~$ bluez-test-adapter powered
0
charles@sita:~$ bluez-test-adapter powered on
charles@sita:~$ bluez-test-adapter powered
0
charles@sita:~$ bluez-test-adapter list
 [ /org/bluez/793/hci0 ]
    Name = ubuntu-0
    Powered = 0
    Devices = dbus.Array([dbus.ObjectPath('/org/bluez/793/hci0/dev_00_11_67_00_03_BD'), dbus.ObjectPath('/org/bluez/793/hci0/dev_2C_44_01_D9_F8_F0')], signature=dbus.Signature('o'), variant_level=1)
    DiscoverableTimeout = 0
    PairableTimeout = 0
    Discoverable = 0
    Address = 60:D8:19:AA:F3:8B
    Discovering = 0
    Pairable = 1
    Class = 0x000000
    UUIDs = dbus.Array([dbus.String(u'00001000-0000-1000-8000-00805f9b34fb'), dbus.String(u'00001001-0000-1000-8000-00805f9b34fb'), dbus.String(u'0000112d-0000-1000-8000-00805f9b34fb'), dbus.String(u'00001112-0000-1000-8000-00805f9b34fb'), dbus.String(u'0000111f-0000-1000-8000-00805f9b34fb'), dbus.String(u'0000111e-0000-1000-8000-00805f9b34fb'), dbus.String(u'0000110c-0000-1000-8000-00805f9b34fb'), dbus.String(u'0000110e-0000-1000-8000-00805f9b34fb'), dbus.String(u'00001103-0000-1000-8000-00805f9b34fb'), dbus.String(u'0000110a-0000-1000-8000-00805f9b34fb'), dbus.String(u'0000110b-0000-1000-8000-00805f9b34fb')], signature=dbus.Signature('s'), variant_level=1)
charles@sita:~$ dpkg -s bluez
Package: bluez
Status: install ok installed
Priority: optional
Section: admin
Installed-Size: 2375
Maintainer: Ubuntu Developers <email address hidden>
Architecture: i386
Multi-Arch: foreign
Version: 4.101-0ubuntu8b1