examples/bfs.v autofree bug

[scroot]

V version: V 0.2.2 6dcf72f

OS: Ubuntu 18.04

What did you do? build $VROOT/examples/bfs.v

v -autofree bfs.v ./bfs

What did you expect to see? normal

What did you see instead? Graph: {'A': ['B', 'C'], 'B': ['A', 'D', 'E'], 'C': ['A', 'F'], 'D': ['B'], 'E': ['B', 'F'], 'F': ['C', 'E']} free(): double free detected in tcache 2 7ff38cf5818b : at ???: RUNTIME ERROR: abort() called 7ff38cfaa47c : by ???