Make it possible to renew aliased service tickets

We always allow aliases in the service principal when processing
AS-REQs and TGS-REQs.  If the ticket we issued is presented back to us
in a TGS-REQ as a header ticket for renewal or similar, we should
allow aliases when looking up its key to decode the AP-REQ.

https://github.com/krb5/krb5/commit/81ceb5352dd3bc11a546d818107d0c4a896cee44
Author: Greg Hudson <ghudson@mit.edu>
Commit: 81ceb5352dd3bc11a546d818107d0c4a896cee44
Branch: master
 src/kdc/kdc_util.c |    6 +++---
 src/tests/t_kdb.py |    8 ++++++++
 2 files changed, 11 insertions(+), 3 deletions(-)