[krbdev.mit.edu #2198] krb5_get_init_creds_keytab() corrupts keytab structure

[Public Submitter via RT]

When starting the 1st iteration through the keytab file after calling krb5_kt_default(), 
calls to krb5_get_init_creds_keytab() will NULL out the FILE * in the krb5_keytab 
structure.  Subsequent iterations will crash the program with a NULL pointer dereference.  
See attached sample program.