virtual/krb5-0-r1 is marked as stable (amd64 and x86) app-crypt/heimdal-1.5.3-r2 is marked as unstable (~amd64 and ~x86) Either heimdal-1.5.3-r2 needs to be bumped to stable, or krb5-0-r1 needs to be changed to require the older heimdal.
*** This bug has been marked as a duplicate of bug 518006 ***