net: do not add multiple connect and finish listeners when multiple Socket.destroySoon's were scheduled
#384
| Job | Run time |
|---|---|
| 1m 36s | |
| 1h 1m 2s | |
| 40m 28s | |
| 37m 31s | |
| 31m 45s | |
| 2h 52m 22s |