Fix use of high bit in heap during heap repack. This can potentially limit max repository size.
Fix use of high bit in heap during heap repack.
This can potentially limit max repository size.

Also redo code to reduce the memory required for a
repack

bk: 550aac66qFzDuL9z6cNdc7vy9UEBvw
bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper,bitkeeper-scm/bitkeeper