[before updating a recursive node, be sure to detag it.
John Meacham <john@repetae.net>**20070517045256] hunk ./C/FromGrin2.hs 400
-    let tmp' = cast nt (if vv < v0 then f_DETAG v' else v')
+    let tmp' = cast nt (f_DETAG v') -- (if vv < v0 then f_DETAG v' else v')