Detect unmodified files being updated during move-update.

* subversion/libsvn_client/resolved.c
  (svn_client_resolve): Add sleep for timestamps.

* subversion/libsvn_wc/wc_db_update_move.c
  (update_working_file): Detect unmodified local file and install
   pristine rather than merging.

* subversion/tests/cmdline/stat_tests.py
  (get_text_timestamp): Add string to exception.
  (no_text_timestamp): New helper.
  (move_update_timestamps): New test.
  (test_list): Add new test.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1455898 13f79535-47bb-0310-9956-ffa450edef68