summary: show active bookmark even if not at current changeset
Before this change, 'hg summary' would not show the active bookmark
unless it pointed to the working directory parent. After this change, it
will show it in parentheses, like so:
parent: 18581:
f0ff45fe6700 tip
summary: simplify handling of active bookmark
branch: default
bookmarks: [crew]
commit: (clean)
update: (current)