largefiles: use the optional badfn argument when building a matcher

The monkey patching in cat() can't be fixed, because it still delegates to the
original bad().  Overriding commands.cat() should go away in favor overriding
cmdutil.cat() anyway, and that matcher can be wrapped with matchmod.badmatch().

hgext/largefiles/lfutil.py

@@ -241,16 +241,18 b' def linktousercache(repo, hash):'
 def getstandinmatcher(repo, rmatcher=None):
     '''Return a match object that applies rmatcher to the standin directory'''
     standindir = repo.wjoin(shortname)
+
+    # no warnings about missing files or directories
+    badfn = lambda f, msg: None
+
     if rmatcher and not rmatcher.always():
         pats = [os.path.join(standindir, pat) for pat in rmatcher.files()]
-        match = scmutil.match(repo[None], pats)
+        match = scmutil.match(repo[None], pats, badfn=badfn)
         # if pats is empty, it would incorrectly always match, so clear _always
         match._always = False
     else:
         # no patterns: relative to repo root
-        match = scmutil.match(repo[None], [standindir])
-    # no warnings about missing files or directories
-    match.bad = lambda f, msg: None
+        match = scmutil.match(repo[None], [standindir], badfn=badfn)
     return match
 
 def composestandinmatcher(repo, rmatcher):