[Dev-luatex] Assertion `pdf_doc->occurences!=0' failed

The code shown below triggers the following assertion: .../source/texk/web2c/luatexdir/image/pdftoepdf.w:844: void unrefPdfDocument(char*): Assertion `pdf_doc->occurences!=0' failed. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \directlua{ local i = 1 while i < 10000 do local pages = img.scan{filename='foo.pdf'}.pages print('Run:', i, 'pages:', pages) i = i + 1 end } \bye %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% On my side this example runs for about 3000 to 6000 iterations before triggering this assertion. But with some real code I can trigger it frequently with less than 200 iterations. Andreas