E122: false positive: continuation line missing indentation or outdented

It seems there's a false positive for E122.

Consider the following snippet

# pep8test.py
def foo(bar):
    pass

# valid:
{
    'title': (
        'Brixton Summer Solstice Roof Party 2015 With DJ Kon'
        ' (3 Hr Sunset Set)'
    ),
}

# valid:
{
    'time_london':
        foo('hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhello'),
}

# valid:
{
    'time_london':
        'hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhello',
    'title': (
        'Brixton Summer Solstice Roof Party 2015 With DJ Kon'
        ' (3 Hr Sunset Set)'
    ),
}


# invalid:
{
    'time_london':
        foo('hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhello'),
    'title': (
        'Brixton Summer Solstice Roof Party 2015 With DJ Kon'
        ' (3 Hr Sunset Set)'
    ),
}

When running pep8 I get:

pep8test.py:37:5: E122 continuation line missing indentation or outdented

Reproduce the E122 report from the examples in pep8test.py, then trace the E122 checker in the repository's Python implementation. Done means the three valid snippets produce no E122 warning while the marked invalid snippet still reports the expected indentation error.