[CentOS-devel] koji build failure

Sometime back in January I submitted the then-current Xen4CentOS dom0
package to build in the CBS for C6, and it worked out of the box:

https://cbs.centos.org/koji/buildinfo?buildID=601

After finishing up my mad month of writing slides, my holiday, and
then clearing my developer backlog, I tried again with the most recent
kernel version, and it failed:

https://cbs.centos.org/koji/buildinfo?buildID=851

I looked at a diff between the two specfiles, and couldn't see
anything that might have prompted this change; so I went back to try
to build the same SRPM I built back in January; and it also failed in
exactly the same way:

https://cbs.centos.org/koji/taskinfo?taskID=8943

I did subsequently build a new set of xen packages, so it's not an
issue with the build system in general, just an issue with the kernel
package.

The actual error message is this one:

DEBUG util.py:333:  Executing command: ['/usr/bin/yum',
'--installroot', '/var/lib/mock/virt6-el6-build-1391-2327/root/',
'groupinstall', 'build', '--setopt=tsflags=nocontexts'] with env
{'LANG': 'en_GB', 'TERM': 'vt100', 'SHELL': '/bin/bash',
'LC_MESSAGES': 'C', 'PROMPT_COMMAND': 'echo -n "<mock-chroot>"',
'PATH': '/usr/bin:/bin:/usr/sbin:/sbin', 'HOME': '/builddir',
'HOSTNAME': 'mock'}
DEBUG util.py:283:  Error: Package: glibc-headers-2.12-1.149.el6.i686 (build)
DEBUG util.py:283:             Requires: kernel-headers >= 2.2.1
DEBUG util.py:283:   You could try using --skip-broken to work around
the problem
DEBUG util.py:283:   You could try running: rpm -Va --nofiles --nodigest
DEBUG util.py:283:  Error: Package: glibc-headers-2.12-1.149.el6.i686 (build)
DEBUG util.py:283:             Requires: kernel-headers
DEBUG util.py:373:  Child return code was: 1

I feel a bit dumb here, but I really have no idea what koji or mock
are doing, so I have no real idea how to proceed to debug what's going
on here.  Can anyone give me a hand?

 -George