Description of problem:

While working on https://bugzilla.redhat.com/show_bug.cgi?id=1315278

Version-Release number of selected component (if applicable):
6.2 Snap 4

How reproducible:
Always

Steps to Reproduce:
1.  Attempt to perform an incremental update to a content view via the Errata page with at least one errata

Actual results:
Task errors on this step:

Actions::Pulp::Repository::CopyErrata


with this traceback from pulp:

Traceback (most recent call last):
      File "/usr/lib/python2.7/site-packages/celery/app/trace.py", line 240, in trace_task
        R = retval = fun(*args, **kwargs)
      File "/usr/lib/python2.7/site-packages/pulp/server/async/tasks.py", line 473, in __call__
        return super(Task, self).__call__(*args, **kwargs)
      File "/usr/lib/python2.7/site-packages/pulp/server/async/tasks.py", line 103, in __call__
        return super(PulpTask, self).__call__(*args, **kwargs)
      File "/usr/lib/python2.7/site-packages/celery/app/trace.py", line 437, in __protected_call__
        return self.run(*args, **kwargs)
      File "/usr/lib/python2.7/site-packages/pulp/server/managers/repo/unit_association.py", line 273, in associate_from_repo
        units=transfer_units)
      File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/importer.py", line 57, in import_units
        return associate.associate(source_repo, dest_repo, import_conduit, config, units)
      File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/associate.py", line 65, in associate
        group_ids, rpm_names, rpm_search_dicts = identify_children_to_copy(associated_units)
      File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/associate.py", line 302, in identify_children_to_copy
        rpm_search_dicts.extend(unit.rpm_search_dicts)
      File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/db/models.py", line 475, in rpm_search_dicts
        checksumtype=checksumtype)
      File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/db/models.py", line 362, in __init__
        super(RpmBase, self).__init__(*args, **kwargs)
      File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/db/models.py", line 134, in __init__
        kwargs['checksumtype'] = verification.sanitize_checksum_type(kwargs['checksumtype'])
      File "/usr/lib/python2.7/site-packages/pulp/plugins/util/verification.py", line 67, in sanitize_checksum_type
        lowercase_checksum_type = checksum_type.lower()
    PulpExecutionException: Pulp exception occurred: PulpExecutionException
  spawned_tasks: []


Expected results:
Incremental update succeeds 

Additional info: