metadataonlyctx: replace "changeset()[0]" to "manifestnode()" As Yuya pointed out [1], "changeset()[0]" could be simplified to "manifestnode()". I didn't notice that method earlier. It should definitely be used - it's easier to read, and faster. [1]: https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-March/095716.html