Comment 4 for bug 562418

It looks like this is caused by the build rules and only affects packages run through pkg-create-dbgsym (in the archive) because PPA and self built packages work right.

The ddeb's aren't being built properly with xserver 1.7.x where the build rules have changed, they're only a few kb.
http://ddebs.ubuntu.com/pool/main/x/xorg-server/

Also, for mesa which does:

        dh_strip -plibgl1-mesa-swx11 --dbg-package=libgl1-mesa-swx11-dbg
        dh_strip -plibgl1-mesa-glx --dbg-package=libgl1-mesa-glx-dbg
        dh_strip -plibgl1-mesa-dri --dbg-package=libgl1-mesa-dri-dbg

the -dbg packages do not have valid CRC's but the -dbgsym's do work properly. This also does not affect PPA builds where the -dbg packages actually build correctly and work.

The debian/rules for xorg-server:
http://git.debian.org/?p=pkg-xorg/xserver/xorg-server.git;a=blob;f=debian/rules;h=eb5928547f257fa52e2fb52b335ce470870d9cb2;hb=refs/heads/ubuntu

and for mesa:
http://git.debian.org/?p=pkg-xorg/lib/mesa.git;a=blob;f=debian/rules;h=f661e9d59eba8ba5ee45dcc7954a7d6e0d652766;hb=refs/heads/ubuntu

Build log for an improperly stripped xorg-server:
http://launchpadlibrarian.net/43932202/buildlog_ubuntu-lucid-i386.xorg-server_2:1.7.6-2ubuntu3_FULLYBUILT.txt.gz