Tests pandas.tests.test_graphics.XXX fail
https://launchpadlibrarian.net/96431877/buildlog_ubuntu-precise-amd64.pandas_0.7.2-ubuntu0~1987~precise1_FAILEDTOBUILD.txt.gz

```
pandas.tests.test_tseries.test_pad_backfill_object_segfault ... ok
pandas.tests.test_tseries.test_arrmap ... ok
pandas.tests.test_tseries.test_series_grouper ... ok

======================================================================
ERROR: test_boxplot (pandas.tests.test_graphics.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 109, in test_boxplot
    _check_plot_works(df.boxplot)
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 136, in _check_plot_works
    fig = plt.gcf()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 369, in gcf
    return figure()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 343, in figure
    **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager
    window = Tk.Tk()
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1688, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
TclError: no display name and no $DISPLAY environment variable

======================================================================
ERROR: test_hist (pandas.tests.test_graphics.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 120, in test_hist
    _check_plot_works(df.hist)
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 136, in _check_plot_works
    fig = plt.gcf()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 369, in gcf
    return figure()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 343, in figure
    **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager
    window = Tk.Tk()
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1688, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
TclError: no display name and no $DISPLAY environment variable

======================================================================
ERROR: test_plot (pandas.tests.test_graphics.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 67, in test_plot
    _check_plot_works(df.plot, grid=False)
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 136, in _check_plot_works
    fig = plt.gcf()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 369, in gcf
    return figure()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 343, in figure
    **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager
    window = Tk.Tk()
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1688, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
TclError: no display name and no $DISPLAY environment variable

======================================================================
ERROR: test_plot_bar (pandas.tests.test_graphics.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 89, in test_plot_bar
    _check_plot_works(df.plot, kind='bar')
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 136, in _check_plot_works
    fig = plt.gcf()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 369, in gcf
    return figure()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 343, in figure
    **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager
    window = Tk.Tk()
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1688, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
TclError: no display name and no $DISPLAY environment variable

======================================================================
ERROR: test_plot_int_columns (pandas.tests.test_graphics.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 126, in test_plot_int_columns
    _check_plot_works(df.plot, legend=True)
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 136, in _check_plot_works
    fig = plt.gcf()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 369, in gcf
    return figure()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 343, in figure
    **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager
    window = Tk.Tk()
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1688, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
TclError: no display name and no $DISPLAY environment variable

======================================================================
ERROR: test_hist (pandas.tests.test_graphics.TestSeriesPlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 46, in test_hist
    _check_plot_works(self.ts.hist)
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 136, in _check_plot_works
    fig = plt.gcf()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 369, in gcf
    return figure()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 343, in figure
    **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager
    window = Tk.Tk()
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1688, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
TclError: no display name and no $DISPLAY environment variable

======================================================================
ERROR: test_plot (pandas.tests.test_graphics.TestSeriesPlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 36, in test_plot
    _check_plot_works(self.ts.plot, label='foo')
  File "/build/buildd/pandas-0.7.2/debian/python-pandas/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 136, in _check_plot_works
    fig = plt.gcf()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 369, in gcf
    return figure()
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 343, in figure
    **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager
    window = Tk.Tk()
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1688, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
TclError: no display name and no $DISPLAY environment variable

----------------------------------------------------------------------
Ran 1475 tests in 31.196s

```
