dv3d plotting ad changing attributes breaks dv3d

[doutriaux1]

In [1]: dsc=x.create3d_scalar()

In [2]: x.plot(s,dsc)
Warning, can't open data file 'None'
initCamera: Camera => ((0.0, 0.0, 540.0), (0.0, 0.0, 0.0), (0.0, 1.0, 0.0)) 
Out[2]: <vcs.displayplot.Dp at 0x11afea230>

In [3]: dsc.axes="xyt"

In [4]: x.clear(); x.plot(s,dsc)
 saved state data to file  <closed file '/lgm/uvcdat/2.2.0/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/DV3D/data/state.txt', mode 'w' at 0x11afb9db0>
initCamera: Camera => ((0.0, 0.0, 540.0), (0.0, 0.0, 0.0), (0.0, 1.0, 0.0)) 
Out[4]: <vcs.displayplot.Dp at 0x11afea320>

fails but

In [1]: dsc=x.create3d_scalar()

In [2]: dsc.axes="xyt"

In [3]: x.plot(s,dsc)

works