"Packages cannot be authenticated" when doing an apt-get in the gate

Something is up with the mirrors we are getting packages from, and we'll get periodic issues like the following:

2014-02-25 18:51:12.736 | WARNING: The following packages cannot be authenticated!
2014-02-25 18:51:12.740 | libgssrpc4 libkadm5clnt-mit8 libkdb5-6 libkadm5srv-mit8 bridge-utils
2014-02-25 18:51:12.744 | libsigsegv2 gawk libaio1 libcaca0 libgfortran3 liblcms1 liblua5.1-0
2014-02-25 18:51:12.748 | mysql-common libmysqlclient18 libpcrecpp0 libsdl1.2debian libxslt1.1 libxss1
2014-02-25 18:51:12.753 | acl seabios vgabios qemu-common librados2 librbd1 qemu-utils qemu-kvm
2014-02-25 18:51:12.757 | libyajl1 tcl8.5 tk8.5 blt btrfs-tools msr-tools cpu-checker cryptsetup
2014-02-25 18:51:12.761 | libnetfilter-conntrack3 dnsmasq-base dnsmasq-utils docutils-common
2014-02-25 18:51:12.766 | docutils-doc dstat ebtables febootstrap fuse-utils genisoimage libsysfs2
2014-02-25 18:51:12.770 | iputils-arping wwwconfig-common javascript-common jfsutils comerr-dev
2014-02-25 18:51:12.775 | krb5-multidev kvm-ipxe libapparmor1 libblas3gf libboost-system1.46.1
2014-02-25 18:51:12.780 | libboost-filesystem1.46.1 libboost-program-options1.46.1
2014-02-25 18:51:12.785 | libboost-thread1.46.1 libconfig-general-perl libjs-jquery-metadata
2014-02-25 18:51:12.789 | libjs-jquery-tablesorter libjs-underscore libjs-sphinxdoc liblapack3gf
2014-02-25 18:51:12.793 | libnspr4-dev libnuma1 libpaper1 libpaper-utils libpq5 libkrb5-dev libpq-dev
2014-02-25 18:51:12.797 | libsasl2-dev libtidy-0.99-0 libutempter0 libxenstore3.0 libvirt0 libxml2-dev
2014-02-25 18:51:12.801 | libxslt1-dev locate watershed lvm2 memcached mongodb-clients mongodb-server
2014-02-25 18:51:12.805 | python-support msgpack-python ntfsprogs open-iscsi-utils open-iscsi
2014-02-25 18:51:12.809 | pkg-config python-logilab-common python-logilab-astng pylint python-amqplib
2014-02-25 18:51:12.813 | python-anyjson python-beautifulsoup python-bson python-carrot
2014-02-25 18:51:12.817 | python-cherrypy3 python-cmd2 python-coverage python-dateutil
2014-02-25 18:51:12.821 | python-decorator python-dingus python-roman python-docutils
2014-02-25 18:51:12.825 | python-egenix-mxtools python-egenix-mxdatetime python-greenlet
2014-02-25 18:51:12.829 | python-eventlet python-feedparser python-formencode python-gflags
2014-02-25 18:51:12.833 | python-gridfs python-imaging python-markupsafe python-jinja2 python-kombu
2014-02-25 18:51:12.837 | python-libxml2 python-lxml python-sqlalchemy python-tempita python-migrate
2014-02-25 18:51:12.841 | python-mysqldb python-netifaces python-nose python-numpy python-openid
2014-02-25 18:51:12.845 | python-paste python-pastedeploy python-setuptools python-pastescript
2014-02-25 18:51:12.849 | python-pip python-pygments python-pymongo python-pysqlite2 python-routes
2014-02-25 18:51:12.853 | python-scgi sphinx-common python-sphinx python-sqlalchemy-ext python-stompy
2014-02-25 18:51:12.857 | python-suds python-tk python-unittest2 python-utidylib python-virtualenv
2014-02-25 18:51:12.862 | python-xattr reiserfsprogs sg3-utils sphinx-doc sqlite3 sysstat libibverbs1
2014-02-25 18:51:12.866 | librdmacm1 tgt xbitmaps xfsprogs xterm zfs-fuse kpartx libffi-dev libhivex0
2014-02-25 18:51:12.870 | scrub zerofree libguestfs0 libldap2-dev python-guestfs python-iso8601
2014-02-25 18:51:12.874 | python-lockfile python-mox python-qpid python-webob socat sysfsutils vim-nox
2014-02-25 18:51:12.878 | vlan
2014-02-25 18:51:12.882 | E: There are problems and -y was used without --force-yes
2014-02-25 18:51:12.886 | +++ failed
2014-02-25 18:51:12.890 | +++ local r=100
2014-02-25 18:51:12.894 | ++++ jobs -p
2014-02-25 18:51:12.898 | +++ kill
2014-02-25 18:51:12.902 | stack.sh failed: full log in /opt/stack/new/devstacklog.txt.2014-02-25-185101

Logstash query: http://logstash.openstack.org/#eyJzZWFyY2giOiJtZXNzYWdlOlwiV0FSTklORzogVGhlIGZvbGxvd2luZyBwYWNrYWdlcyBjYW5ub3QgYmUgYXV0aGVudGljYXRlZFwiIiwiZmllbGRzIjpbXSwib2Zmc2V0IjowLCJ0aW1lZnJhbWUiOiI2MDQ4MDAiLCJncmFwaG1vZGUiOiJjb3VudCIsInRpbWUiOnsidXNlcl9pbnRlcnZhbCI6MH0sInN0YW1wIjoxMzkzNzExNjQxMzMzfQ==