I have removed the two occurrances of "\'" then 
"make de.po" runs on a fresh checkout (trunk rev 4189)
and thus de.po is finally updated and ready for translation.

For the new version I've remove the obsolete line:
# roundup.pot revision 1.8
I believe this should be done for all *.po files
and the $ID$ line should also go unless keyword expansion is enabled.

Attached a new fresh de.po which can be used as base 
to now update the translation. (Which I will try next.)