The testcase connects server 2 to server 1 as a slave and then server 3 with the same UUID connects, disconnecting server 2. The testcase greps that there is one binlog zombie dump thread kill, but finds two. This can happen if server 3 receives ER_NET_READ_INTERRUPTED soon after its connect and is forced to silently reconnect.
The testcase connects server 2 to server 1 as a slave and then server 3 with the same UUID connects, disconnecting server 2. The testcase greps that there is one binlog zombie dump thread kill, but finds two. This can happen if server 3 receives ER_NET_ READ_INTERRUPTE D soon after its connect and is forced to silently reconnect.