passing matplotlib options to line2d

[DMonniaux]

The line2d documentation claims "Any MATPLOTLIB line option may also be passed in. E.g. [...]".

Yet there does not seem to be any way to pass dash_capstyle to Matplotlib; 

line2d([(0,0),(0,1)],dash_capstyle='round')        

[...]

RuntimeError: Error in line(): option 'dash_capstyle' not valid.

I even tried to set dash_capstyle in matplotlibrc but the setting seems ignored.