diff -r 6641e941ef1e -r ff1a9aa48cfd app/django/template/loaders/app_directories.py
--- a/app/django/template/loaders/app_directories.py	Tue Oct 14 12:36:55 2008 +0000
+++ b/app/django/template/loaders/app_directories.py	Tue Oct 14 16:00:59 2008 +0000
@@ -33,11 +33,19 @@
 app_template_dirs = tuple(app_template_dirs)
 
 def get_template_sources(template_name, template_dirs=None):
+    """
+    Returns the absolute paths to "template_name", when appended to each
+    directory in "template_dirs". Any paths that don't lie inside one of the
+    template dirs are excluded from the result set, for security reasons.
+    """
     if not template_dirs:
         template_dirs = app_template_dirs
     for template_dir in template_dirs:
         try:
             yield safe_join(template_dir, template_name)
+        except UnicodeDecodeError:
+            # The template dir name was a bytestring that wasn't valid UTF-8.
+            raise
         except ValueError:
             # The joined path was located outside of template_dir.
             pass