TestReleaseAutoIPs.test__calls_update_host_maps_for_next_ip_managed_subnet can fail randomly

[Mike Pontillo]

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ERROR: maasserver.models.tests.test_interface.TestReleaseAutoIPs.test__calls_update_host_maps_for_next_ip_managed_subnet
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_StringException: Traceback (most recent call last):
  File "/tmp/tarmac/branch.0YArZb/src/maastesting/runtest.py", line 68, in _run_user
    result = function(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/testtools/testcase.py", line 616, in _run_test_method
    return self._get_test_method()()
  File "/tmp/tarmac/branch.0YArZb/src/maasserver/models/tests/test_interface.py", line 2104, in test__calls_update_host_maps_for_next_ip_managed_subnet
    subnet=subnet, interface=interface)
  File "/tmp/tarmac/branch.0YArZb/src/maasserver/testing/factory.py", line 657, in make_StaticIPAddress
    ipaddress.save()
  File "/tmp/tarmac/branch.0YArZb/src/maasserver/models/cleansave.py", line 38, in save
    return super(CleanSave, self).save(*args, **kwargs)
  File "/tmp/tarmac/branch.0YArZb/src/maasserver/models/timestampedmodel.py", line 70, in save
    return super(TimestampedModel, self).save(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 545, in save
    force_update=force_update, update_fields=update_fields)
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 573, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 654, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 687, in _do_insert
    using=using, raw=raw)
  File "/usr/lib/python2.7/dist-packages/django/db/models/manager.py", line 232, in _insert
    return insert_query(self.model, objs, fields, **kwargs)
  File "/usr/lib/python2.7/dist-packages/django/db/models/query.py", line 1511, in insert_query
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/usr/lib/python2.7/dist-packages/django/db/models/sql/compiler.py", line 898, in execute_sql
    cursor.execute(sql, params)
  File "/usr/lib/python2.7/dist-packages/django/db/backends/util.py", line 53, in execute
    return self.cursor.execute(sql, params)
  File "/usr/lib/python2.7/dist-packages/django/db/utils.py", line 99, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/usr/lib/python2.7/dist-packages/django/db/backends/util.py", line 53, in execute
    return self.cursor.execute(sql, params)
IntegrityError: duplicate key value violates unique constraint "maasserver_staticipaddress_ip_key"
DETAIL: Key (ip)=(55.104.24.60) already exists.

(see first stack trace here if this is unreadable: http://paste.ubuntu.com/13005385/)