Workaround launchpad error 'Unable to handle http code 502: Bad Gateway'

[Para Siva]

Current raring smoke tests are impacted by launchpad connectivity issue which report the following error

This occurs in two stages,
1. When starting the utah job to get the preseed, runlists from lp: the error is as follows

sudo -u utah -i run_utah_tests.py -p lp:~ubuntu-server-dev/ubuntu-test-cases/server-tests-raring/preseeds/default.preseed -i /var/cache/utah/iso/raring-server-i386.iso lp:~ubuntu-server-dev/ubuntu-test-cases/server-tests-raring/runlists/default.run -x /etc/utah/bridged-network-vm.xml
usage: run_utah_tests.py [-h] [-m MACHINETYPE] [-v VARIANT] [-s SERIES]
                         [-t TYPE] [-a ARCH] [-n] [-d] [-j] [-f FILES]
                         [-o OUTDIR] [--dumplogs] [--outputpreseed] [-i IMAGE]
                         [-p PRESEED] [-b BOOT]
                         [--rewrite {all,minimal,casperonly,none}] [-k KERNEL]
                         [-r INITRD] [--name NAME] [-e EMULATOR] [-x XML]
                         [-g GIGABYTES] [--diskbus DISKBUS]
                         runlist
run_utah_tests.py: error: argument -p/--preseed: Bazaar export error: Invalid http response for http://bazaar.launchpad.net/~ubuntu-server-dev/ubuntu-test-cases/server-tests-raring/preseeds/default.preseed/.bzr/branch-format: Unable to handle http code 502: Bad Gateway

The impacted job :
https://jenkins.qa.ubuntu.com/view/Raring/view/Smoke%20Testing/job/raring-server-i386-smoke-default/77/console

2: When getting the test code after the installation within the client machine: The error is as follows
- cmd_type: testsuite_fetch
  command: bzr export usit lp:~javier.collado/ubuntu-test-cases/desktop/testsuites/usit
  returncode: 3
  start_time: '2013-01-23 11:54:39'
  stderr: |-
    You have not informed bzr of your Launchpad ID, and you must do this to
    write to Launchpad or access private data. See "bzr help launchpad-login".
    bzr: ERROR: Invalid http response for http://bazaar.launchpad.net/~javier.collado/ubuntu-test-cases/desktop/testsuites/usit/.bzr/branch-format: Unable to handle http code 502: Bad Gateway

The impacted job:
https://jenkins.qa.ubuntu.com/view/Raring/view/Smoke%20Testing/job/raring-desktop-i386-smoke-encrypted_home/48/

This error occurred about 25% of the tests and lanuchpad-ops first suggested to use bzr+ssh rather than http but then later from the information from cdimages that this has been occurring once in a while due to possible lp overload, downtime etc, the proposed solution is to add a workaround to retry after some time.

[Javier Collado (javier.collado)]

Thanks for the complete report.

The retry strategy is the easiest to use since that needs only a minor update
in the code while, as discussed on irc, the bzr+ssh one requires to use a
launchpad user with an authorized ssh key. Hence, I'll try first to use the
retry strategy.

If that doesn't work, we can go for the second options since we're going to use
a launchpad user account for tarmac in the future anyway.