diff -r 83a94c2fe6f4 -r c18204fd35b0 mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Sun May 01 16:11:42 2011 +0200
+++ b/mercurial/cmdutil.py	Sat Apr 30 23:27:00 2011 +0200
@@ -1314,14 +1314,15 @@
     match.bad = lambda x, y: bad.append(x) or oldbad(x, y)
     names = []
     wctx = repo[None]
-    existing = None
-    if scmutil.showportabilityalert(ui):
-        existing = dict([(fn.lower(), fn) for fn in wctx])
+    cca = None
+    abort, warn = scmutil.checkportabilityalert(ui)
+    if abort or warn:
+        cca = scmutil.casecollisionauditor(ui, abort, wctx)
     for f in repo.walk(match):
         exact = match.exact(f)
         if exact or f not in repo.dirstate:
-            if existing:
-                scmutil.checkcasecollision(ui, f, existing)
+            if cca:
+                cca(f)
             names.append(f)
             if ui.verbose or not exact:
                 ui.status(_('adding %s\n') % match.rel(join(f)))