Fixed --repository option when handling relative path

When specifying relative path to --repository option, 'log' and
'diff' were unable to find the files specified. Here's the fix.

mercurial/hg.py

@@ -634,7 +634,7 b' class localrepository:'
             if not create and not os.path.isdir(self.path):
                 raise RepoError("repository %s not found" % self.path)
 
-        self.root = path
+        self.root = os.path.abspath(path)
         self.ui = ui
 
         if create: