Resolve the issue for which I added a regression test in r1603497.

* subversion/libsvn_client/commit.c
  (post_process_commit_item): Add svn_error_tracer
  (post_process_no_commit_item): New function like post_process_commit_item,
    but just handling the no-commit operations.
  (svn_client_commit6): Only call post_process_commit_item on items that we
    are really committing, and post_process_no_commit_item on everything else.

* subversion/tests/cmdline/lock_tests.py
  (commit_file_unlock): Update expected result to no longer
    expect an invalid bump.
  (lock_commit_bump): Remove XFail marker.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1603617 13f79535-47bb-0310-9956-ffa450edef68