`Retrieval failure from indexer: context canceled` when successful but _fast_

Testing out some http failures from web3.storage that now seem to be passing, I'm guessing related to https://github.com/web3-storage/freeway/issues/87 where the content hasn't quite been pushed out to the caching layer. But this is interesting behaviour from lassie:

```
go run ./cmd/lassie/ fetch -p --protocols http bafybeihmqcb3kjyib3jed5cudpvfyf7ydquh4rjykma34qxnmj6von66d4/6762.png
... [gobs of indexer candidates, repeating only 2 peer IDs many many times, one for bitswap and one for http (w3s)]
Received 9 blocks / 1.4 MiB...
Fetched [bafybeihmqcb3kjyib3jed5cudpvfyf7ydquh4rjykma34qxnmj6von66d4] from [QmUA9D3H7HeCYsirB3KmPSvZh3dNXMZas6Lwgr4fv1HTTp]:
Duration: 560.943093ms
Blocks: 9
Bytes: 1.4 MiB
Retrieval failure from indexer: context canceled
```

This happened after running it a couple of times, note how fast the download is, so this is super speedy now it's cached in CF from web3.storage, and I think lassie trips over itself and we get a context cancellation in the indexer streaming results that we count as an actual failure. But we got the data we wanted, and it validated, so should be an overall success.