repoview: use repo.revs() instead of a private revset method

Breaks an import cycle.

mercurial/repoview.py

@@ -9,7 +9,7 b''
 import copy
 import phases
 import util
-import obsolete, revset
+import obsolete
 
 
 def hideablerevs(repo):
@@ -28,8 +28,9 b' def computehidden(repo):'
         cl = repo.changelog
         firsthideable = min(hideable)
         revs = cl.revs(start=firsthideable)
-        blockers = [r for r in revset._children(repo, revs, hideable)
-                      if r not in hideable]
+        tofilter = repo.revs(
+            '(%ld) and children(%ld)', list(revs), list(hideable))
+        blockers = [r for r in tofilter if r not in hideable]
         for par in repo[None].parents():
             blockers.append(par.rev())
         for bm in repo._bookmarks.values():

tests/test-module-imports.t

@@ -38,5 +38,4 b' these may expose other cycles.'
   mercurial/ui.py mixed imports
      stdlib:    formatter
      relative:  config, error, scmutil, util
-  Import cycle: mercurial.repoview -> mercurial.revset -> mercurial.repoview
   Import cycle: mercurial.cmdutil -> mercurial.context -> mercurial.subrepo -> mercurial.cmdutil -> mercurial.cmdutil