Kerberos no longer prerequires rsh to build succesfully (krb5-1.3.1). It builds succesfully without rsh installed on the system. Please remove this BuildPrereq from the spec file.
How have you determined this? The src/appl/bsd/configure script still guesses that rsh is installed as /usr/ucb/rsh if rsh is not found at compile-time. Marking won't fix because it's still needed for this test to determine the correct path.