Fix uncached sequence creation from iterator

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/common/SequenceStorageNodes.java

@@ -4165,7 +4165,7 @@ private SequenceStorage executeImpl(Object iterator, int len) {
                         }
                     }
                 }
-                return create().createStorageUninitialized(null, iterator, GetNextNode.getUncached(), IsBuiltinClassProfile.getUncached(), len);
+                return create().createStorageUninitialized(null, iterator, GetNextNode.getUncached(), IsBuiltinClassProfile.getUncached(), len >= 0 ? len : START_SIZE);
             }
         }