Migration Plugin

According to the original report , the failure is seen for RHEL 8 Appstream repos.

I was able to reproduce it with this repo but not Appstream:

• https://fixtures.pulpproject.org/rpm-with-sha-1-modular/

  Traceback (most recent call last):
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/sync.py", line 294, in run
      self.update_content(metadata_files, url)
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/sync.py", line 627, in update_content
      purge.purge_unwanted_units(metadata_files, self.conduit, self.config, catalog)
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/purge.py", line 45, in purge_unwanted_units
      remove_missing_errata(metadata_files, conduit)
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/purge.py", line 148, in remove_missing_errata
      updateinfo.process_package_element)
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/purge.py", line 277, in get_remote_units
      for unit in package_info_generator:
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/repomd/packages.py", line 64, in package_list_generator
      package_info = process_func(element)
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/repomd/updateinfo.py", line 33, in process_package_element
      pkglists = map(_parse_pkglist, element.findall('pkglist') or [])
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/repomd/updateinfo.py", line 102, in _parse_pkglist
      return map(_parse_collection, element.findall('collection') or [])
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/repomd/updateinfo.py", line 116, in _parse_collection
      ret['module'] = _parse_module(module_elements[0])
    File "/usr/lib/python2.7/site-packages/pulp_rpm/plugins/importers/yum/repomd/updateinfo.py", line 171, in _parse_module
      'name': element.attrib['name'],
  KeyError: 'name'

It's unclear if the content has to be migrated or if the problem can be reproduced if the upstream repos are synced to pulp3 directly.