When including inkscape-generated EPS files into LaTeX, then generating
Postscript and then using psnup on the resulting Postscript all text
after the inkscape image lands on the next page. This also seems to
screw up the postscript structuring because there is now one page more.

Only the last image on a page generated by psnup seems to be affected

Steps to reproduce:
- I'm including a test-file t.tex and cc_by_sa.svg, I hope reportbug
  lets me do that :-)
- Issue the following series of commands:
  latex t.tex
  dvips t
  psnup -n 4 t.ps t-4.ps
  gv t-4.ps

You need LaTeX and psutils installed.
for the last step you can use almost any postscript interpreter.

The problem indicates that the inkscape-generated postscript probably
doesn't conform to some postscript guidelines. I was unable to fix the
postscript by editing. My current workaround is to run the
inkscape-generated postscript through Ghostscripts eps2eps -- this fixes
the eps files in question.

The problem is caused by the Incscape EPS file that places the userdict
on top of the dictionary stack and brings in all the context it has. In
particular, it brings an unwanted definition of /showpage.

Patching the EPS file solves the problem.

--- cc_by_sa.eps 2021-06-02 23:49:29.426574732 -0400
+++ cc_by_sa-fixed.eps 2021-06-02 23:50:11.731325295 -0400
@@ -11,7 +11,7 @@
  /cairo_eps_state save def
  /dict_count countdictstack def
  /op_count count 1 sub def
-userdict begin
+100 dict begin
  /q { gsave } bind def
  /Q { grestore } bind def
  /cm { 6 array astore concat } bind def

My copy of Incscape, Inkscape 0.92.5 (2060ec1f9f, 2020-04-08) already
has a similar fix. I believe that this bug can be closed as fixed.