new extension: fetch -> combine pull and merge/update
pull changes from remote repo.
if changes add new head: merge with new head, commit result.
else: update working dir to new head.
this makes useful command like git 'pull' command.
adding foo
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
pushing to ../2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files