emerge mozilla-firefox
Calculating dependencies... done!

>>> Emerging (1 of 1) www-client/mozilla-firefox-1.5.0.5 to /
 * Previously fetched: mozilla-firefox-1.5.0.5-patches-0.1.tar.bz2 MD5 ;-) ...                            [ ok ]
 * Previously fetched: mozilla-firefox-1.5.0.5-patches-0.1.tar.bz2 RMD160 ;-) ...                         [ ok ]
 * Previously fetched: mozilla-firefox-1.5.0.5-patches-0.1.tar.bz2 SHA1 ;-) ...                           [ ok ]
 * Previously fetched: mozilla-firefox-1.5.0.5-patches-0.1.tar.bz2 SHA256 ;-) ...                         [ ok ]
 * Previously fetched: mozilla-firefox-1.5.0.5-patches-0.1.tar.bz2 size ;-) ...                           [ ok ]
 * Previously fetched: firefox-1.5.0.5-source.tar.bz2 MD5 ;-) ...                                         [ ok ]
 * Previously fetched: firefox-1.5.0.5-source.tar.bz2 RMD160 ;-) ...                                      [ ok ]
 * Previously fetched: firefox-1.5.0.5-source.tar.bz2 SHA1 ;-) ...                                        [ ok ]
 * Previously fetched: firefox-1.5.0.5-source.tar.bz2 SHA256 ;-) ...                                      [ ok ]
 * Previously fetched: firefox-1.5.0.5-source.tar.bz2 size ;-) ...                                        [ ok ]
 * Previously fetched: firefox-fr-1.5.0.5.xpi MD5 ;-) ...                                                 [ ok ]
 * Previously fetched: firefox-fr-1.5.0.5.xpi RMD160 ;-) ...                                              [ ok ]
 * Previously fetched: firefox-fr-1.5.0.5.xpi SHA1 ;-) ...                                                [ ok ]
 * Previously fetched: firefox-fr-1.5.0.5.xpi SHA256 ;-) ...                                              [ ok ]
 * Previously fetched: firefox-fr-1.5.0.5.xpi size ;-) ...                                                [ ok ]
 * checking ebuild checksums ;-) ...                                                                      [ ok ]
 * checking auxfile checksums ;-) ...                                                                     [ ok ]
 * checking miscfile checksums ;-) ...                                                                    [ ok ]
 * checking firefox-1.5.0.5-source.tar.bz2 ;-) ...                                                        [ ok ]
 * checking mozilla-firefox-1.5.0.5-patches-0.1.tar.bz2 ;-) ...                                           [ ok ]
 * checking firefox-fr-1.5.0.5.xpi ;-) ...                                                                [ ok ]
>>> Unpacking source...
>>> Unpacking firefox-1.5.0.5-source.tar.bz2 to /var/tmp/portage/mozilla-firefox-1.5.0.5/work
>>> Unpacking mozilla-firefox-1.5.0.5-patches-0.1.tar.bz2 to /var/tmp/portage/mozilla-firefox-1.5.0.5/work
 * Unpacking firefox-fr-1.5.0.5.xpi to /var/tmp/portage/mozilla-firefox-1.5.0.5/work
[/var/tmp/portage/mozilla-firefox-1.5.0.5/distdir/firefox-fr-1.5.0.5.xpi]
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of /var/tmp/portage/mozilla-firefox-1.5.0.5/distdir/firefox-fr-1.5.0.5.xpi or
        /var/tmp/portage/mozilla-firefox-1.5.0.5/distdir/firefox-fr-1.5.0.5.xpi.zip, and cannot find /var/tmp/portage/mozilla-firefox-1.5.0.5/distdir/firefox-fr-1.5.0.5.xpi.ZIP, period.

!!! ERROR: www-client/mozilla-firefox-1.5.0.5 failed.
Call stack:
  ebuild.sh, line 1545:   Called dyn_unpack
  ebuild.sh, line 711:   Called src_unpack
  mozilla-firefox-1.5.0.5.ebuild, line 83:   Called xpi_unpack 'firefox-fr-1.5.0.5.xpi'
  mozextension.eclass, line 32:   Called die

!!! failed to unpack firefox-fr-1.5.0.5.xpi
!!! If you need support, post the topmost build error, and the call stack if relevant.