package install sporadic failures

I've seen this sporadically (maybe 5-10% of the time? complete guestimate) when doing the initial puppet run on a node after the bare metal Ubuntu install is done via cobbler

What I see is that some subset of our packages fail to install during the initial run:

debug: Puppet::Type::Package::ProviderApt: Executing '/usr/bin/apt-get -q -y -o DPkg::Options::=--force-confold install euca2ools'
err: /Stage[main]/Nova::Utilities/Nova::Utilities::Nova::Utilities::Install[euca2ools]/Package[euca2ools]/ensure: change from purged to present failed: Execution of '/usr/bin/apt-get -q -y -o DPkg::Options::=--force-confold install euca2ools' returned 100: Reading package lists...
Building dependency tree...
Reading state information...
The following extra packages will be installed:
  cloud-utils libgmp10 libyaml-0-2 python-boto python-crypto python-m2crypto
  python-paramiko python-yaml
Suggested packages:
  python-crypto-dbg python-crypto-doc
The following NEW packages will be installed:
  cloud-utils euca2ools libgmp10 libyaml-0-2 python-boto python-crypto
  python-m2crypto python-paramiko python-yaml
0 upgraded, 9 newly installed, 0 to remove and 0 not upgraded.
Need to get 2321 kB of archives.
After this operation, 14.1 MB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  libgmp10 libyaml-0-2 python-m2crypto python-boto python-yaml cloud-utils
E: There are problems and -y was used without --force-yes

However, some packages do install successfully. In this example, the next task executed was a successful install:

debug: Puppet::Type::Package::ProviderApt: Executing '/usr/bin/dpkg-query -W --showformat ${Status} ${Package} ${Version}\n bridge-utils'
debug: Puppet::Type::Package::ProviderApt: Executing '/usr/bin/apt-get -q -y -o DPkg::Options::=--force-confold install bridge-utils'
notice: /Stage[main]/Nova::Compute/Package[bridge-utils]/ensure: ensure changed 'purged' to 'present'

If I try to manually install the package which failed, I find that it's failing due to inability by apt to authenticate the package:

# apt-get install euca2ools
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  cloud-utils libgmp10 libyaml-0-2 python-boto python-crypto python-m2crypto
  python-paramiko python-yaml
Suggested packages:
  python-crypto-dbg python-crypto-doc
The following NEW packages will be installed:
  cloud-utils euca2ools libgmp10 libyaml-0-2 python-boto python-crypto
  python-m2crypto python-paramiko python-yaml
0 upgraded, 9 newly installed, 0 to remove and 0 not upgraded.
Need to get 2,321 kB of archives.
After this operation, 14.1 MB of additional disk space will be used.
Do you want to continue [Y/n]?
WARNING: The following packages cannot be authenticated!
  libgmp10 libyaml-0-2 python-m2crypto python-boto python-yaml cloud-utils
Install these packages without verification [y/N]? n
E: Some packages could not be authenticated
#

If I then manually run apt-get update and then apt-get install euca2ools, apt authenticates and installs the package successfully