translation fails when literal block is in a list

[nobodxbodon]

Excuse me if this is a user issue, as I'm new to reStructuredText and Sphinx.
After putting the literal block into a list, this test case fails:
$ tox -e py36 tests/test_intl.py::test_additional_targets_should_be_translated

[tk0miya]

It seems docutils (reST parser) does not assign source filename to literal_block under bullet list:

from docutils import nodes
from docutils.core import publish_doctree


text = ("::\n"
        "\n"
        "  literal_block on root\n"
        "\n"
        "* ::\n"
        "\n"
        "    literal_block inside bullet_list\n")
doctree = publish_doctree(text, source_path='<string>')

# literal_block on root has correct source
assert isinstance(doctree[0], nodes.literal_block)
assert doctree[0].source == '<string>'
assert doctree[0].line == 3

# bullet_list also has correct source
assert isinstance(doctree[1], nodes.bullet_list)
assert doctree[1].source == '<string>'
assert doctree[1].line == 5

# but literal_block inside bullet_list does not
assert isinstance(doctree[1][0][0], nodes.literal_block)
assert doctree[1][0][0].source == '<string>'
assert doctree[1][0][0].line == 7

$ python test_literal_block.py
Traceback (most recent call last):
  File "test_literal_block.py", line 26, in <module>
    assert doctree[1][0][0].source == '<string>'
AssertionError

[tk0miya]

Fixed by #4943