Only let Redirect and Unauthorized string exceptions propagate.

lib/python/Products/PageTemplates/CHANGES.txt

@@ -10,5 +10,9 @@ Page Template changes
 
         - Adopted Zope-style CHANGES.txt and HISTORY.txt
         - Improved execution performance
+        - nocall: paths are back in.
 
       Bugs Fixed
+
+        - TALES expressions let any string exception through, not just
+          Redirect and Unauthorized.

lib/python/Products/PageTemplates/TALES.py

@@ -87,7 +87,7 @@
 An implementation of a generic TALES engine
 """
 
-__version__='$Revision: 1.16 $'[11:-2]
+__version__='$Revision: 1.17 $'[11:-2]
 
 import re, sys, ZTUtils
 from MultiMapping import MultiMapping
@@ -284,7 +284,7 @@ class Context:
         except TALESError:
             raise
         except:
-            if isinstance(sys.exc_info()[0], StringType):
+            if sys.exc_info()[0] in ('Redirect', 'Unauthorized'):
                 raise
             raise TALESError, (`expression`, sys.exc_info()), sys.exc_info()[2]
         else: