hgview #20996 hgview crashes when the repository is empty [validation pending]

hgview crash if you'd like to see an empty repository:

$ hg init test_repo
$ cd test_repo
$ hg qv
Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.5/hgviewlib/qt4/hgrepoview.py", line 186, in resizeEvent
  File "/usr/lib/pymodules/python2.5/hgviewlib/qt4/hgrepoview.py", line 201, in resizeColumns
    w = model.maxWidthValueForColumn(c)
  File "/usr/lib/pymodules/python2.5/hgviewlib/qt4/hgrepomodel.py", line 271, in maxWidthValueForColumn
    return _maxwidth[column](self, self.repo)
  File "/usr/lib/pymodules/python2.5/hgviewlib/qt4/hgrepomodel.py", line 111, in <lambda>
    key=lambda x: len(x))[-1],
IndexError: list index out of range
done in1.6.0
load left0.000
closed by#e0ad6f151b89 Don't crash/close when exploring an empty repository (closes #20996)