got error about plural-forms

during install of module CAPTCHA ( on a german language translated drupal site ) there is warning about "plural-forms"

since i took a lock to de.po :

there is a

"Plural-Forms: nplurals=INTEGER; plural=EXPRESSION;\n"

in the file, which should be IMHO

"Plural-Forms: nplurals=2; plural=(n!=1);\n"

like other tranlations use. As far i can see at least the urkain translation is also affected.

regards
Peter