Fixed the multiple (incorrect) extension problem for some materials links. Fixes issue #1947.

- Legacy-Id: 11104

ietf/doc/views_doc.py

@@ -549,8 +549,9 @@ def document_main(request, name, rev=None):
             extension = os.path.splitext(g)[1]
             t = os.path.splitext(g)[1].lstrip(".")
             url = doc.href()
+            urlbase, urlext = os.path.splitext(url)
             if not url.endswith("/") and not url.endswith(extension):
-                url += extension
+                url = urlbase + extension
 
             if extension == ".txt":
                 content = get_document_content(basename, pathname + extension, split=False)