DataQualityDict.populate() doesn't work

The method DataQualityDict.populate should execute with no arguments, but it doesn't:

>>> from gwpy.segments import DataQualityDict
>>> vdffile = '/path/to/veto-definer.xml'
>>> vdf = DataQualityDict.from_veto_definer_file(vdffile)
>>> vdf.populate()
Traceback (most recent call last):
  File "test-vdf.py", line 7, in <module>
    vdf.populate()
  File "/home/duncan.macleod/opt/gwpysoft/lib/python2.6/site-packages/gwpy/segments/flag.py", line 1239, in populate
    segments = SegmentList(map(Segment, segments))
TypeError: argument 2 to map() must support iteration

(thanks to @rpfisher for reporting)