Am Dienstag, 12. Februar 2013 schrieb Ludovic Courtès:
> It’s actually slightly more complex: you need to select those packages
> that are installed and for which either a newer version is available
> (per ‘version-string>?’, see gnu-maintenance.scm; should be moved to
> utils.scm)

This reminds me:
   guix-package -i libjpeg
still installs version 8d and not 9, so apparently, there is no check on 
the version number.

And
   guix-package -A jpeg
prints
   libjpeg 9       out     gnu/packages/libjpeg.scm:27:3
   libjpeg 8d      out     gnu/packages/libjpeg.scm:27:3
which is strange since libjpeg-9 is indeed defined around line 27, but 
libjpeg-8 comes later in the file.

Andreas