Followup to r29075: Instead of using custom user names, just use the generic 'second user' in the test suite.  This comes in response to authz failures when running ra_dav and ra_svn tests.
Followup to r29075: Instead of using custom user names, just use the generic
'second user' in the test suite.  This comes in response to authz failures when
running ra_dav and ra_svn tests.

* subversion/tests/cmdline/log_tests.py
  (merge_history_repos): Replace 'copier' and 'merger' with 'jconstant'

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion