Avoid an unneeded extra ra session for svn copy WC URL. We don't need an ra
session with working copy commit support for this scenario.

* subversion/libsvn_client/copy.c
  (wc_to_repos_copy): Conditionalize some ev2 code and reparent the ra session
    instead of creating a new one.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1551564 13f79535-47bb-0310-9956-ffa450edef68