fixed scoping for local on for tag.

tests/testfor.jet

@@ -1,6 +1,9 @@
 #!../jet-2.0
 <jet cgi="true" name1="localname" filterblanklines="true" trimlines="true">
- <for name="ix" start="1" end="5" step=".1">
-  -->#[ix]<--
+ <set name="iz" value="8" scope="local" />
+ <for name="ix" start="1" end="10" step="1" scope="local" iz="#[iz]">
+  #[scope]
+  <dump file="dump.txt" />
+  -->[iz]-[iy]-#[ix]<--
  </for>
 </jet>