Created attachment 5187 [details]
minimal testcase

MuPDF renders this very simple file pretty much inverse to what Adobe Reader
does.

A path with several subpaths (moveto lineto segments) is not having all the subpaths closed, which leads 
to the left line of the outer rectangle in the minimal test case not existing, thus the entire outer rectangle 
is not filled.

The fix is to make sure all subpaths are closed when doing pdf_showpath with doclose set.

Committed a patch that closes open subpath segments when filling a path.