An issue with erase block number calculation has been identified in
https://sourceforge.net/mailarchive/forum.php?thread_name=49DE59D6.9000000%40maginst.com&forum_name=urjtag-development
and subsequently fixed with SVN r1488.
The similar functionality found in flashmsbin() has probably similar problems. Fixing them is postponed unless we have a way to test the MSBIN flash code.