--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -299,6 +299,7 @@ def clone(ui, source, dest = None, **opt
     if not (source.startswith("http://") or
             source.startswith("hg://") or
             source.startswith("old-http://")):
+        source = os.path.abspath(source)
         d1 = os.stat(dest).st_dev
         d2 = os.stat(source).st_dev
         if d1 == d2: link = 1