Rewrite smerge and add hack to address merging problems when importing patches with duplicate work.
Rewrite smerge and add hack to address merging problems when importing patches
with duplicate work.

bk: 3bd9bd5cHtqiCxGt2TEAG9dl2gdDUQ
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