`sort -u | uniq` is completely redundant, calling grep for every
status-pair is unnecessary, `contains` doesn't take the word "in" as
special.
None of these are critical and there's basically no performance benefit
since this function is utterly dominated by hg calls.
This doesn't add anything except slowing the function down by about
33%. Checking for a branch is just as good and that is displayed in the
prompt anyway.
