Prevent the conflict resolver from searching paths in revision zero.
Prevent the conflict resolver from searching paths in revision zero.

Problem uncovered by the tree conflict raised at the end of conflict_tests 25
which causes the resolver to search for a related path in r0 while trying to
figure out a nested move committed in r2.

* subversion/libsvn_client/conflicts.c
  (rev_below): New helper function for decrementing revision numbers.
   If we're already at the very bottom (r1), stay there.
   Assert that callers don't try to search paths at invalid revisions or r0.
  (check_move_ancestry, find_nested_move, find_deleted_rev,
   conflict_tree_get_details_local_missing,
   get_incoming_delete_details_for_reverse_addition,
   describe_incoming_reverse_deletion_upon_merge,
   resolve_merge_incoming_added_dir_merge,
   merge_incoming_added_dir_replace): Use the new helper function instead of
    hardcoding the pattern "rev - 1".


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1771905 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion