pull up r25469 from trunk

pull up r25469 from trunk

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 r25469 | ghudson | 2011-11-11 12:01:12 -0500 (Fri, 11 Nov 2011) | 14 lines

 ticket: 6430
 subject: Avoid looping when preauth can't be generated
 target_version: 1.10
 tags: pullup

 If we receive a PREAUTH_REQUIRED error and fail to generate any real
 preauthentication, error out immediately instead of continuing to
 generate non-preauthenticated requests until we hit the loop count.

 There is a lot of room to generate a more meaningful error about why
 we failed to generate preauth (although in many cases the answer may
 be too complicated to explain in an error message), but that requires
 more radical restructuring of the preauth framework.

ticket: 6430
version_fixed: 1.10
status: resolved

git-svn-id: svn://anonsvn.mit.edu/krb5/branches/krb5-1-10@25501 dc483132-0cff-0310-8789-dd5450dbe970