revset: split post-parsing stage from match()

_makematcher() will be reused by new matchany(ui, specs, repo=None) function
I'll add by the next patch.

mercurial/revset.py

@@ -2667,6 +2667,9 b' def match(ui, spec, repo=None):'
     if repo:
         lookup = repo.__contains__
     tree = parse(spec, lookup)
+    return _makematcher(ui, tree, repo)
+
+def _makematcher(ui, tree, repo):
     if ui:
         tree = findaliases(ui, tree, showwarning=ui.warn)
     tree = foldconcat(tree)