F19 packstack installs regularly fail with

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Error: Could not prefetch glance_image provider 'glance': Execution of '/usr/bin/glance -T services -I glance -K cbde8203258a4cf5 -N http://192.168.0.2:35357/v2.0/ show ID' returned 1
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I've figured out this is due to puppet-glance which is doing [1]

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(auth_glance('index').split("\n")[2..-1] || []).collect do |line|
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i.e. it assumes the top two lines are headers.  Unfortunately the command is giving a warning about backports, which takes up two lines and then the puppet modules are confused (hence the "show ID" in the output)

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[root@host-192-168-0-2 ~]# strace -f -o /tmp/foo.txt /usr/bin/glance -T services -I glance -K cbde8203258a4cf5 -N http://192.168.0.2:35357/v2.0/ image-list
/usr/lib/python2.7/site-packages/keyring/core.py:166: UserWarning: Module backports was already imported from /usr/lib64/python2.7/site-packages/backports/__init__.pyc, but /usr/lib/python2.7/site-packages is being added to sys.path
  pkg_resources = __import__('pkg_resources')
+--------------------------------------+--------+-------------+------------------+----------+--------+
| ID                                   | Name   | Disk Format | Container Format | Size     | Status |
+--------------------------------------+--------+-------------+------------------+----------+--------+
| 26ed571b-ff55-459c-80ca-911ae8e42b4f | cirros | qcow2       | bare             | 13147648 | active |
+--------------------------------------+--------+-------------+------------------+----------+--------+
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I found a related bz#1022686 where this same sort of thing was happening with keystone

[1] https://github.com/stackforge/puppet-glance/blob/master/lib/puppet/provider/glance.rb#L111