If there is no Userdata, loguserdata.py should not try to execute it.

[Clint Byrum]

loguserdata.py explodes if userdata is not an executable:

Traceback (most recent call last):
  File "/var/lib/cloud/instance/scripts/loguserdata.py", line 52, in <module>
    returncode = main(log)
  File "/var/lib/cloud/instance/scripts/loguserdata.py", line 44, in main
    returncode = call([userdata_path], log)
  File "/var/lib/cloud/instance/scripts/loguserdata.py", line 26, in call
    p = subprocess.Popen(args, stdout=log, stderr=log)
  File "/usr/lib/python2.7/subprocess.py", line 679, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1259, in _execute_child
    raise child_exception
OSError: [Errno 8] Exec format error
2013-03-13 03:56:11,929 - util.py[WARNING]: Failed running /var/lib/cloud/instance/scripts/loguserdata.py [1]

This is a completely normal situation and should just be logged.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/24399

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/24400

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/24399
Committed: http://github.com/openstack/heat/commit/fbea93155097d283b3b1b479d2c3ade3c233d287
Submitter: Jenkins
Branch: master

commit fbea93155097d283b3b1b479d2c3ade3c233d287
Author: Angus Salkeld <email address hidden>
Date: Thu Mar 14 12:33:23 2013 +1100

    loguserdata: prevent shadowing of arguments and globals

    cleaning this up for bug 1154641

    Change-Id: I95271bdeba1bba29e78af79de4e2173d07750e4f
    Signed-off-by: Angus Salkeld <email address hidden>

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/24400
Committed: http://github.com/openstack/heat/commit/655e377d456b090a061f8c34a050284ed2e4b6ee
Submitter: Jenkins
Branch: master

commit 655e377d456b090a061f8c34a050284ed2e4b6ee
Author: Angus Salkeld <email address hidden>
Date: Thu Mar 14 14:21:55 2013 +1100

    loguserdata: handle exceptions from running the userdata

    - log the exceptions so the user can diagnose issues.

    bug 1154641
    Change-Id: Ic085c9f062255a9fa44b3e31b464c9ebd19a947c
    Signed-off-by: Angus Salkeld <email address hidden>