topic: remove a silly duplicate in a revset Spotted by Pulkit Goyal. More performance win seems to exists here, but we starts with the obvious.

topics: show changesetcount, troubledcount and headscount by default

topics: use stack.stack() instead of stack.stackdata() stack.stackdata() also calls stack.stack() internally. Moreover if we just want to calculate changesetcount, troubled count, it will be cheap to calculate using stack.stack rather than stackdata().