push: add bookmarks to the unified bundle2 push We use the `pushkey` part to exchange bookmark updates within the unified bundle2 push. Note that this only applies on update (moving a bookmark known on both sides) since bookmark export (creation of a new bookmark on remote) is apparently done outside of the _push function.

test-bundle2: add bookmark movement to the push test If we add bookmarks to bundle2, we need a way to test the new code. Tests are changed beforehand to highlight that inclusion of bookmarks in bundle does not introduce any behavior changes.

push: use stepsdone to control bookmark push If bookmark are to be integrated in the unified bundle2, we need a way to disable the old-style push.

push: move bookmark discovery with other discovery steps The discovery of necessary bookmark updates is now done within the "discovery phase". This opens the door to the inclusion of bookmarks in a unified bundle2 push.

pushbookmark: split an ultra-long line into a saner version We make a temporary variable for the remote bookmark data and we do not expand all elements from `bookmark.compare` since we are going to use only one.

revert: drop dead code for untracked files Untracked files are handled through status now.

revert: handle unknown files through status This will allow us to drop the code dedicated to this special case.

revert: drop more dead code Now that we detect all clean files, we do not need this clause anymore.