templater: add function that expands internal literal templates This will be used when rendering nested formatter items with the default template, e.g. fm.nested('parents', tmpl='{rev}:{node|formatnode}', sep=' ') ^^^^^^^^^^^^^^^^^^^^^^^ the default item template

bookmarks: use isrevsymbol() for detecting collision with existing symbol Differential Revision: https://phab.mercurial-scm.org/D3167

debugwhyunstable: add support for revsets Differential Revision: https://phab.mercurial-scm.org/D3166