[MIGRATIONS] detect completion of site directory move more robustly
[MIGRATIONS] detect completion of site directory move more robustly

zooley/hubzero-cms,zweidner/hubzero-cms,anthonyfuentes/hubzero-cms,anthonyfuentes/hubzero-cms,zweidner/hubzero-cms,anthonyfuentes/hubzero-cms,zweidner/hubzero-cms,zweidner/hubzero-cms,zooley/hubzero-cms,zooley/hubzero-cms,anthonyfuentes/hubzero-cms,zooley/hubzero-cms