Correct usage of the check_log_chain() function, which was being used as a log chain validity predicate, but is implemented more as an assertion.  Also, improve its argument checking.
Correct usage of the check_log_chain() function, which was being used
as a log chain validity predicate, but is implemented more as an
assertion.  Also, improve its argument checking.


* subversion/tests/cmdline/log_tests.py
  (check_log_chain): Tweak doc string.  Check CHAIN list argument for
   content before attempting a pop(), and raise svntest.Failure if
   it's empty.

  (plain_log, log_with_path_args, log_through_copyfrom_history,
   log_limit): Remove unnecessary handling for a return value from
   check_log_chain(), which never actually returns anything (only
   raises exceptions).


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@858247 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion