group object is lost if there is an xform object

This has been reported on the latex issue tracker:
https://github.com/latex3/latex2e/issues/800
but in our opinion it is a problem of the pdftex engine.

If a pdf is included which contains a transparency group and there
is also a xform object is created then pdftex complains  about
multiple pdfs:

pdfTeX warning: pdftex.exe (file ./titel_fg.pdf): PDF inclusion:
multiple pdfs 
with page group included in a single page

It inserts a reference into the page object /Group 6 0 R, but the
referenced object is missing.

I attach the used pdf, but it case that the attachment is lost it
can also be found in the zip in the latex issue.


\pdfcompresslevel=0
\pdfobjcompresslevel=0
\setbox0\hbox{a}
\pdfxform0
\pdfrefxform\pdflastxform
\pdfximage{titel_fg.pdf}
\hbox{\pdfsave
\pdfsetmatrix{0.5 0 0 0.5}%
\rlap{\pdfrefximage\pdflastximage}%
\pdfrestore}

\bye




-- 
Ulrike Fischer 
http://www.troubleshooting-tex.de/