git-remote-bzr fails with "RevisionNotPresent"

When trying to use the git-remote-bzr helper to download lp:ecryptfs in Git format, the process quickly fails with:

$ git clone bzr::bzr+ssh://bazaar.launchpad.net/+branch/ecryptfs/
Cloning into 'ecryptfs'...
Traceback (most recent call last):map 0/249
  File "/usr/lib/python3.9/site-packages/breezy/git/cache.py", line 905, in _get_entry
    return next(entries)[2]
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/breezy/git/object_store.py", line 640, in _lookup_revision_sha1
    return self._cache.idmap.lookup_commit(revid)
  File "/usr/lib/python3.9/site-packages/breezy/git/cache.py", line 923, in lookup_commit
    return self._get_entry((b"commit", revid, b"X"))[:40]
  File "/usr/lib/python3.9/site-packages/breezy/git/cache.py", line 908, in _get_entry
    raise KeyError
KeyError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/breezy/git/object_store.py", line 643, in _lookup_revision_sha1
    return mapping_registry.parse_revision_id(revid)[0]
  File "/usr/lib/python3.9/site-packages/breezy/git/mapping.py", line 529, in revision_id_bzr_to_foreign
    raise errors.InvalidRevisionId(bzr_revid, None)
breezy.errors.InvalidRevisionId: Invalid revision-id {<email address hidden>'} in None

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/breezy/bzr/inventorytree.py", line 932, in iter_files_bytes
    for result in self._repository.iter_files_bytes(repo_desired_files):
  File "/usr/lib/python3.9/site-packages/breezy/bzr/remote.py", line 2347, in iter_files_bytes
    raise errors.RevisionNotPresent(revision_id=missing_key[1],
breezy.errors.RevisionNotPresent: Revision {b'git-v1:e5a1d5d9fb2bac724e45c7d9892a622697b52934'} not present in "b'doc/design__doc/img7.png'".

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/git-remote-bzr", line 52, in <module>
    helper.process(sys.stdin.buffer, sys.stdout.buffer)
  File "/usr/lib/python3.9/site-packages/breezy/git/git_remote_helper.py", line 172, in process
    self.process_line(line, outf)
  File "/usr/lib/python3.9/site-packages/breezy/git/git_remote_helper.py", line 190, in process_line
    self.commands[argv[0].decode()](self, outf, argv)
  File "/usr/lib/python3.9/site-packages/breezy/git/git_remote_helper.py", line 124, in cmd_list
    for ref, git_sha1 in viewitems(refs.as_dict()):
  File "/usr/lib/python3.9/site-packages/dulwich/refs.py", line 210, in as_dict
    ret[key] = self[(base + b'/' + key).strip(b'/')]
  File "/usr/lib/python3.9/site-packages/dulwich/refs.py", line 297, in __getitem__
    _, sha = self.follow(name)
  File "/usr/lib/python3.9/site-packages/dulwich/refs.py", line 269, in follow
    contents = self.read_ref(refname)
  File "/usr/lib/python3.9/site-packages/dulwich/refs.py", line 242, in read_ref
    contents = self.read_loose_ref(refname)
  File "/usr/lib/python3.9/site-packages/breezy/git/refs.py", line 156, in read_loose_ref
    return self.object_store._lookup_revision_sha1(revid)
  File "/usr/lib/python3.9/site-packages/breezy/git/object_store.py", line 645, in _lookup_revision_sha1
    self._update_sha_map(revid)
  File "/usr/lib/python3.9/site-packages/breezy/git/object_store.py", line 468, in _update_sha_map
    self._update_sha_map_revision(revid)
  File "/usr/lib/python3.9/site-packages/breezy/git/object_store.py", line 557, in _update_sha_map_revision
    for path, obj in self._revision_to_objects(
  File "/usr/lib/python3.9/site-packages/breezy/git/object_store.py", line 510, in _revision_to_objects
    for path, obj, bzr_key_data in _tree_to_objects(
  File "/usr/lib/python3.9/site-packages/breezy/git/object_store.py", line 311, in _tree_to_objects
    for (path, file_id), chunks in tree.iter_files_bytes(
  File "/usr/lib/python3.9/site-packages/breezy/bzr/inventorytree.py", line 935, in iter_files_bytes
    raise errors.NoSuchFile(e.file_id)
breezy.errors.NoSuchFile: No such file: b'doc/design__doc/img7.png'