changelog: optimize delayed updates for clone vs pull
pull index updates get redirected to memory, then appended on finalize
clone index updates get sent to 00changelog.i.a, then renamed on finalize
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://www.selenic.com/mercurial/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.