pgf files created by PGF backend are incorrect for paths which extend beyond axes limits

[gibbycu]

It appears that when there is a path outside the plotting limits then not all the path coordinates get plotted. When I run the code below with xmax=1.1 versus xmax=1.0, the axvspan is plotted wrong in latex. Inspection of the pgf file for the two versions of xmax indicates that a \pgfpathlineto command is missing in the xmax=1.1 version. I've traced it to _print_pgf_path() in the backend and the line for points, code in path.iter_segments(transform, clip=clip): which is asking for clipped points.

Python Code

import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(111)

ax.plot([0,1],[0,1],'-k')
ax.set_xlim(0,1)
ax.axvspan(xmin=0.5, xmax=1.1)

fig.savefig('test.pgf')

Latex code

\documentclass {article}
\usepackage{pgf}

\begin{document}
    \begin{figure}
        \centering
        \input{test.pgf}
    \end{figure}
\end{document

Here is a pic of the result after compiled with latex (pdflatex or xelatex)

However, saving to .pdf produces the right result

[mdboom]

The clipping algorithm in matplotlib only works for non-filled objects. I suspect the PGF backend needs to determine if the path is filled, and if so, turn clipping off.

[jenshnielsen]

I think this is a duplicate of #2885