HTTP 412 errors when trying to alter a BugTask using the API

[Graham Binns]

When I try to set the status and importance of a BugTask using the API and then subsequently call lp_save() on that BugTask, I intermittently get an HTTP 412 error:

Traceback (most recent call last):
  File "/home/graham/bin/file-many-bugs.py", line 39, in <module>
    initial_task.lp_save()
  File "/usr/lib/python2.5/site-packages/lazr/restfulclient/resource.py", line 603, in lp_save
    URI(self.self_link), representation, headers)
  File "/usr/lib/python2.5/site-packages/lazr/restfulclient/_browser.py", line 258, in patch
    'PATCH', extra_headers=extra_headers)
  File "/usr/lib/python2.5/site-packages/lazr/restfulclient/_browser.py", line 204, in _request
    raise HTTPError(response, content)
lazr.restfulclient.errors.HTTPError: HTTP Error 412: Precondition Failed

I can't be sure that this isn't an issue with launchpadlib, but given that it started happening immediately after rollout I'm guessing it's server-side.

[Gary Poster (gary)]

I'll ask Leonard for an idea on how to debug this further.