Corrected some DocTypeName entries' prefix value. Made the search code more robust against DocTypeName objects that have an empty prefix value. Fixes ietf-tools#2599. Commit ready for merge.

 - Legacy-Id: 15601

Author: rjsparks

ietf/doc/views_search.py

@@ -292,7 +292,7 @@ def cached_redirect(cache_key, url):
         search_args += "&rfcs=on&activedrafts=on&olddrafts=on"
     else:
         for t in doctypenames:
-            if n.startswith(t.prefix):
+            if t.prefix and n.startswith(t.prefix):
                 search_args += "&doctypes=%s" % t.slug
                 break
         else: