Handle unknown requests better within controllers

guix-data-service/web/revision/controller.scm

@@ -136,7 +136,8 @@
                                           #:path-base path))
          (render-unknown-revision mime-types
                                   conn
-                                  commit-hash)))))
+                                  commit-hash)))
+    (_ #f)))
 
 (define (texinfo->variants-alist s)
   (let ((stexi (texi-fragment->stexi s)))