pull: list bookmarks before pulling changesets (issue3873) Consider a bookmark B that exists both locally and remotely. If B is updated remotely, and then a pull is performed where the pull set contains the new location of B, the bookmark is updated locally. However, if remote B is updated in the middle of a pull to a location not in the pull set, the bookmark won't be updated locally at all. To fix this, list bookmarks before pulling in changesets, not after. This still leaves a race open if B gets moved in between listing bookmarks and pulling in changesets, but the race window is much smaller. Fixing the race properly would require a bundle format upgrade. test-hook.t's output changes because we no longer do two listkeys calls during pull, just one. test-pull-http.t's output changes because we now search for bookmarks before searching for changes.