[root@busta eric]# yum downgrade glibc
Loaded plugins: fs-snapshot, langpacks, presto, refresh-packagekit
Setting up Downgrade Process
Resolving Dependencies
--> Running transaction check
---> Package glibc.x86_64 0:2.14.90-10 will be a downgrade
--> Processing Dependency: glibc-common = 2.14.90-10 for package: glibc-2.14.90-10.x86_64
---> Package glibc.x86_64 0:2.14.90-12 will be erased
--> Finished Dependency Resolution
Error: Package: glibc-common-2.14.90-12.x86_64 (@updates-testing)
           Requires: glibc = 2.14.90-12
           Removing: glibc-2.14.90-12.x86_64 (@updates-testing)
               glibc = 2.14.90-12
           Downgraded By: glibc-2.14.90-10.x86_64 (fedora)
               glibc = 2.14.90-10
Error: Package: glibc-2.14.90-10.x86_64 (fedora)
           Requires: glibc-common = 2.14.90-10
           Installed: glibc-common-2.14.90-12.x86_64 (@updates-testing)
               glibc-common = 2.14.90-12
           Available: glibc-common-2.14.90-10.x86_64 (fedora)
               glibc-common = 2.14.90-10
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest