mined block failed verification
```
p2pool-monero | 2021-11-14 02:29:00.386 I ----- BLOCK ADDED AS ALTERNATIVE ON HEIGHT 2492830
...
p2pool-p2pool | 2021-11-14 02:28:59.5999 P2Pool new main chain block: height = 2492830, id = 7cd83a73057ee654e5fce4748dbe14941daadcecc08d25843c5a9b7a66b275e5, timestamp = 1636856931, reward = 0.816392950182 XMR
...
p2pool-monero | 2021-11-14 02:31:43.581 E mined block failed verification
...
p2pool-p2pool | 2021-11-14 02:31:43.3505 SideChain add_external_block: block f6bfb0c1465a11d851ce832f8e7b7d4496981d52a127a0b79af65eec2e74af6c has enough PoW for Monero network, submitting it
...
p2pool-p2pool | 2021-11-14 02:31:43.3505 P2Pool submit_block: height = 2492832, external blob (2329 bytes)
...
p2pool-xmrig | [2021-11-14 02:32:00.639]  net      new job from p2pool:3333 diff 1000K algo rx/0 height 2492832 (23 tx)
```

Issue:  It looked like p2pool found a block, but it failed to verify and we continued to mine that same height?  It was submitted anyway, and the stats for it showed up briefly on the observer page.  