pdftex "page" colorstack interferre with "page" pdfliteral

Hello,

I've found a buggy behavior of pdftex. Suppose the (minimal) example:

   \chardef\Color=\pdfcolorstackinit page {0 g 0 G}

   \shipout\vbox{
      \pdfcolorstack\Color push {1 0 0 rg}
   }

   \shipout\vbox{
      \pdfliteral page {q 0 1 0 0 k 0 0 100 100 re f Q}
   }

   \end

First box (first page) is empty. Second page should include the rectangle 
at left-bottom of the page, because "page" option is specified. But this 
is not true. You can try it: second page has its rectangle at the top.

If you comment out the \pdfcolorstack line in the first \vbox, then the 
first page is really empty and the second page includes its rectangle at 
the right position.

Where is a problem?

I tested this by pdfTeX from TeXlive 2015.

Petr Olsak