Launchpad gets bogus data from memcached

As seen in the following oopses: OOPS-d2bb7e643b3bec12048bc7bb6b8fdd01 OOPS-c65580688f20f2ecc14f478d296a326e

  TypeError: 'NoneType' object is unsubscriptable

    Traceback (most recent call last):
  Module zope.publisher.publish, line 134, in publish
    result = publication.callObject(request, obj)
  Module lp.services.webapp.publication, line 499, in callObject
    return mapply(ob, request.getPositionalArguments(), request)
  Module zope.publisher.publish, line 109, in mapply
    return debug_call(obj, args)
   - __traceback_info__: <security proxied zope.browserpage.metaconfigure.SimpleViewClass from /srv/launchpad.net/production/launchpad-rev-14933/lib/lp/app/browser/../templates/root-index.pt instance at 0x17bd5bd0>
  Module zope.publisher.publish, line 115, in debug_call
    return obj(*args)
  Module lp.services.webapp.publisher, line 392, in __call__
    return self.render()
  Module lp.services.webapp.publisher, line 377, in render
    return self.template()
  Module zope.app.pagetemplate.viewpagetemplatefile, line 83, in __call__
    return self.im_func(im_self, *args, **kw)
  Module zope.app.pagetemplate.viewpagetemplatefile, line 51, in __call__
    sourceAnnotations=getattr(debug_flags, 'sourceAnnotations', 0),
  Module zope.pagetemplate.pagetemplate, line 113, in pt_render
    strictinsert=0, sourceAnnotations=sourceAnnotations)()
  Module zope.tal.talinterpreter, line 271, in __call__
    self.interpret(self.program)
  Module zope.tal.talinterpreter, line 343, in interpret
    handlers[opcode](self, args)
  Module zope.tal.talinterpreter, line 888, in do_useMacro
    self.interpret(macro)
  Module zope.tal.talinterpreter, line 343, in interpret
    handlers[opcode](self, args)
  Module zope.tal.talinterpreter, line 533, in do_optTag_tal
    self.do_optTag(stuff)
  Module zope.tal.talinterpreter, line 518, in do_optTag
    return self.no_tag(start, program)
  Module zope.tal.talinterpreter, line 513, in no_tag
    self.interpret(program)
  Module zope.tal.talinterpreter, line 343, in interpret
    handlers[opcode](self, args)
  Module zope.tal.talinterpreter, line 531, in do_optTag_tal
    self.no_tag(stuff[-2], stuff[-1])
  Module zope.tal.talinterpreter, line 513, in no_tag
    self.interpret(program)
  Module zope.tal.talinterpreter, line 343, in interpret
    handlers[opcode](self, args)
  Module zope.tal.talinterpreter, line 852, in do_condition
    self.interpret(block)
  Module zope.tal.talinterpreter, line 343, in interpret
    handlers[opcode](self, args)
  Module zope.tal.talinterpreter, line 533, in do_optTag_tal
    self.do_optTag(stuff)
  Module zope.tal.talinterpreter, line 518, in do_optTag
    return self.no_tag(start, program)
  Module zope.tal.talinterpreter, line 513, in no_tag
    self.interpret(program)
  Module zope.tal.talinterpreter, line 343, in interpret
    handlers[opcode](self, args)
  Module zope.tal.talinterpreter, line 946, in do_defineSlot
    self.interpret(slot)
  Module zope.tal.talinterpreter, line 343, in interpret
    handlers[opcode](self, args)
  Module lp.services.memcache.tales, line 319, in do_insertText_tal
    text = self.engine.evaluateText(stuff[0])
  Module lp.services.memcache.tales, line 361, in evaluateText
    text = self.evaluate(expr)
  Module zope.tales.tales, line 696, in evaluate
    return expression(self)
   - /srv/launchpad.net/production/launchpad-rev-14933/lib/lp/app/browser/../templates/root-index.pt
   - Line 147, Column 12
   - Expression: <MemcacheExpr public, 1 hour>
   - Names:
      {'args': (),
       'context': <lp.services.webapp.publisher.RootObject object at 0x4533a90>,
       'default': <object object at 0x2b4f2c2bc490>,
       'loop': {},
       'nothing': None,
       'options': {},
       'repeat': {},
       'request': <lp.services.webapp.servers.LaunchpadBrowserRequest instance URL=https://launchpad.net/index.html>,
       'template': <z3c.ptcompat.ViewPageTemplateFile object at 0x9018150>,
       'view': <zope.browserpage.metaconfigure.SimpleViewClass from /srv/launchpad.net/production/launchpad-rev-14933/lib/lp/app/browser/../templates/root-index.pt object at 0x17bd5bd0>,
       'views': <zope.app.pagetemplate.viewpagetemplatefile.ViewMapper object at 0x15711bd0>}
  Module lp.services.memcache.tales, line 262, in __call__
    cached_chunk = getUtility(IMemcacheClient).get(key)
  Module lp.services.memcache.client, line 50, in get
    return memcache.Client.get(self, key)
  Module memcache, line 779, in get
    return self._get('get', key)
  Module memcache, line 762, in _get
    rkey, flags, rlen, = self._expectvalue(server)
  Module memcache, line 874, in _expectvalue
    if line[:5] == 'VALUE':
TypeError: 'NoneType' object is unsubscriptable