don't fail if keyattribute not found in current basis when no basis s…

…pecified

This is not actually an error, we just need to try another basis
down the list. This is a copypasta bug that was only caught now. :-/

services/pddb/src/backend/basis.rs

@@ -741,7 +741,9 @@ impl BasisCache {
                             index: kcache.descriptor_index,
                         })
                     } else {
-                        return Err(Error::new(ErrorKind::NotFound, "key not found"));
+                        // this is not a hard error, it just means that the key wasn't in this basis.
+                        // that's alright, it could be in one of the other ones!
+                        continue;
                     }
                 }
             }