Description of problem:
I installed a bunch of packages via yum. Installation of selinux-policy-mls
appeared to fail:

Running Transaction
  Installing     : libsepol-devel                                    [1/7] 
  Installing     : libselinux-devel                                  [2/7] 
  Installing     : selinux-doc                                       [3/7] 
  Installing     : selinux-policy-devel                              [4/7] 
  Installing     : policycoreutils-newrole                           [5/7] 
  Installing     : mcstrans                                          [6/7] 
  Installing     : selinux-policy-mls                                [7/7] 
libsepol.context_from_record: type courier_exec_t is not defined
libsepol.context_from_record: could not create context structure
libsepol.context_from_string: could not create context structure
libsepol.sepol_context_to_sid: could not convert
system_u:object_r:courier_exec_t:s0 to sid
invalid context system_u:object_r:courier_exec_t:s0
libsemanage.semanage_install_active: setfiles returned error code 1.
libsemanage.semanage_install_active: Could not copy
/etc/selinux/mls/modules/active/policy.kern to
/etc/selinux/mls/policy/policy.23. (No such file or directory).
semodule:  Failed!

Version-Release number of selected component (if applicable):
Installed: libselinux-devel.i386 0:2.0.64-2.fc9 selinux-doc.noarch 0:1.26-1.1
selinux-policy-devel.noarch 0:3.3.1-69.fc9 selinux-policy-mls.noarch 0:3.3.1-69.fc9
Dependency Installed: libsepol-devel.i386 0:2.0.26-1.fc9 mcstrans.i386
0:0.2.11-1.fc9 policycoreutils-newrole.i386 0:2.0.49-7.fc9