Security update/glibc name change seems to have confused yum

I have a new SL/RHEL6 installation, and yum is refusing to install gcc 
on it. As far as I can make out, a security update that I applied prior 
to my attempt to install gcc has caused problems. Any advice on this 
would be gratefully appreciated. Full story below.

I did a new SL6 install (x86_86) a couple of weeks ago. This was a 
minimal installation, and I didn't install any dev tools, as I intended 
to install them later from yum.

Since then, I've done very little; I installed a few packages (samba, 
xemacs, etc), and I let the system update itself. The update installed 
'kernel', and updated 'kernel-firmware' (see this advisory: 
http://lwn.net/Alerts/436999/).

I now need to install the dev tools (g++, and so on), but I can't. I've 
tried this from gpk-application, and directly from yum. The complete yum 
output is below, but the basic error is:

> Error: Package: glibc-2.12-1.7.el6.i686 (sl)
>            Requires: glibc-common = 2.12-1.7.el6
>            Installed: glibc-common-2.12-1.7.el6_0.5.x86_64 (@sl-security)
>                glibc-common = 2.12-1.7.el6_0.5
>            Available: glibc-common-2.12-1.7.el6.x86_64 (sl)
>                glibc-common = 2.12-1.7.el6
>  You could try using --skip-broken to work around the problem
>  You could try running: rpm -Va --nofiles --nodigest

The security update installed glibc-common-2.12-1.7.el6_0.5.x86_64, but 
it looks like yum can't cope with the name change. Am I right? Is there 
anything I can do about this?

Thanks -

Paul

===================================================================

[root@foo work]# yum clean all
Loaded plugins: refresh-packagekit
Cleaning up Everything
[root@foo work]# yum install gcc-c++
Loaded plugins: refresh-packagekit
epel/metalink                                            |  13 kB 
00:00
epel                                                     | 4.3 kB 
00:00
epel/primary_db                                          | 3.8 MB 
00:16
sl                                                       | 3.2 kB 
00:00
sl/primary_db                                            | 3.8 MB 
00:11
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package gcc-c++.x86_64 0:4.4.4-13.el6 set to be updated
--> Processing Dependency: gcc = 4.4.4-13.el6 for package: 
gcc-c++-4.4.4-13.el6.x86_64
--> Processing Dependency: libstdc++-devel = 4.4.4-13.el6 for package: 
gcc-c++-4.4.4-13.el6.x86_64
--> Processing Dependency: libmpfr.so.1()(64bit) for package: 
gcc-c++-4.4.4-13.el6.x86_64
--> Running transaction check
---> Package gcc.x86_64 0:4.4.4-13.el6 set to be updated
--> Processing Dependency: cpp = 4.4.4-13.el6 for package: 
gcc-4.4.4-13.el6.x86_64
--> Processing Dependency: cloog-ppl >= 0.15 for package: 
gcc-4.4.4-13.el6.x86_64
--> Processing Dependency: glibc-devel >= 2.2.90-12 for package: 
gcc-4.4.4-13.el6.x86_64
---> Package libstdc++-devel.x86_64 0:4.4.4-13.el6 set to be updated
---> Package mpfr.x86_64 0:2.4.1-6.el6 set to be updated
--> Running transaction check
---> Package cloog-ppl.x86_64 0:0.15.7-1.2.el6 set to be updated
--> Processing Dependency: libppl.so.7()(64bit) for package: 
cloog-ppl-0.15.7-1.2.el6.x86_64
--> Processing Dependency: libppl_c.so.2()(64bit) for package: 
cloog-ppl-0.15.7-1.2.el6.x86_64
---> Package cpp.x86_64 0:4.4.4-13.el6 set to be updated
---> Package glibc-devel.x86_64 0:2.12-1.7.el6 set to be updated
--> Processing Dependency: glibc = 2.12-1.7.el6 for package: 
glibc-devel-2.12-1.7.el6.x86_64
--> Processing Dependency: glibc-headers = 2.12-1.7.el6 for package: 
glibc-devel-2.12-1.7.el6.x86_64
--> Processing Dependency: glibc-headers for package: 
glibc-devel-2.12-1.7.el6.x86_64
--> Running transaction check
---> Package glibc.i686 0:2.12-1.7.el6 set to be updated
--> Processing Dependency: glibc-common = 2.12-1.7.el6 for package: 
glibc-2.12-1.7.el6.i686
--> Processing Dependency: libfreebl3.so(NSSRAWHASH_3.12.3) for package: 
glibc-2.12-1.7.el6.i686
--> Processing Dependency: libfreebl3.so for package: 
glibc-2.12-1.7.el6.i686
---> Package glibc-headers.x86_64 0:2.12-1.7.el6 set to be updated
--> Processing Dependency: kernel-headers >= 2.2.1 for package: 
glibc-headers-2.12-1.7.el6.x86_64
--> Processing Dependency: kernel-headers for package: 
glibc-headers-2.12-1.7.el6.x86_64
---> Package ppl.x86_64 0:0.10.2-11.el6 set to be updated
--> Running transaction check
---> Package glibc.i686 0:2.12-1.7.el6 set to be updated
--> Processing Dependency: glibc-common = 2.12-1.7.el6 for package: 
glibc-2.12-1.7.el6.i686
---> Package kernel-headers.x86_64 0:2.6.32-71.el6 set to be updated
---> Package nss-softokn-freebl.i686 0:3.12.7-1.1.el6 set to be updated
--> Finished Dependency Resolution
Error: Package: glibc-2.12-1.7.el6.i686 (sl)
            Requires: glibc-common = 2.12-1.7.el6
            Installed: glibc-common-2.12-1.7.el6_0.5.x86_64 (@sl-security)
                glibc-common = 2.12-1.7.el6_0.5
            Available: glibc-common-2.12-1.7.el6.x86_64 (sl)
                glibc-common = 2.12-1.7.el6
  You could try using --skip-broken to work around the problem
  You could try running: rpm -Va --nofiles --nodigest
[root@foo work]#