When the add part of a move is handled during post-commit, clear out its
moved_from information.

Easy fixup, knowing that sqlite has an index with exactly this information.

* subversion/libsvn_wc/wc-queries.sql
  (STMT_CLEAR_MOVED_TO_FROM_DEST): New query.

* subversion/libsvn_wc/wc_db.c
  (moved_descendant_commit): Enable assertion. But not for production yet.
  (commit_node): When committing some kind of add, clear moved-to information
    if there is any. This improves the intermediate state during commit.
    (Note that this might be seen outside qlite transactions)


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1444023 13f79535-47bb-0310-9956-ffa450edef68