vfs: use 'vfs' module directly in 'mercurial.debugcommand'

Now that the 'vfs' classes moved in their own module, lets use the new module
directly. We update code iteratively to help with possible bisect needs in the
future.

mercurial/debugcommands.py

@@ -63,6 +63,7 b' from . import ('
     templater,
     treediscovery,
     util,
+    vfs as vfsmod,
 )
 
 release = lockmod.release
@@ -76,7 +77,7 b' def debugancestor(ui, repo, *args):'
     """find the ancestor revision of two revisions in a given index"""
     if len(args) == 3:
         index, rev1, rev2 = args
-        r = revlog.revlog(scmutil.vfs(pycompat.getcwd(), audit=False), index)
+        r = revlog.revlog(vfsmod.vfs(pycompat.getcwd(), audit=False), index)
         lookup = r.lookup
     elif len(args) == 2:
         if not repo:
@@ -452,7 +453,7 b' def debugdag(ui, repo, file_=None, *revs'
     spaces = opts.get('spaces')
     dots = opts.get('dots')
     if file_:
-        rlog = revlog.revlog(scmutil.vfs(pycompat.getcwd(), audit=False),
+        rlog = revlog.revlog(vfsmod.vfs(pycompat.getcwd(), audit=False),
                              file_)
         revs = set((int(r) for r in revs))
         def events():