Fix: Remove logic that trimmed the last byte from transaction ID in publishReferenceScripts function (Demo Setup)

[f0rm4l1ty]

I reported this in Discord, but this is a fix for the Hydra Head "Getting started" demo located here https://hydra.family/head-protocol/docs/getting-started

Running the ./seed-devnet.sh command would invoke a function called publishReferenceScripts that saves a transaction id to the .env file named HYDRA_SCRIPTS_TX_ID. This function included a piped command: head -c -1 which removed the last byte from the outputted transaction id.

This must have been utilized in a previous version, however now it incorrectly trims the last byte from the transaction id, causing it to be invalid (incorrect length). Running the docker compose up -d hydra-node-{1,2,3} would cause an error like so, and cause the containers to crash and keep restarting:

option --hydra-scripts-tx-id: RawBytesHexErrorBase16DecodeFail "0e2114c7a09c171ce8a8a5ba282fa2a47056a1c6415d4aaecbbb44093cdf2e7" "invalid bytestring size"

I have confirmed that removing this specific command fixes the issue and the Hydra nodes successfully start up.

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• CHANGELOG updated or not needed
• Documentation updated or not needed
• Haddocks updated or not needed
• No new TODOs introduced or explained herafter

[noonio]

Thanks for looking into this @f0rm4l1ty !

Can you tell me what the output of this command is, on your computer?

echo "a\nb\nc" | tr '\n' ','

For me, on NixOS, I get a trailing comma. I'm assuming on your system you don't get that?

-- Edit: Disregard, this isn't the problem.

[noonio]

Ah, I think I see the problem @f0rm4l1ty ; in fact it's because that code has been changed in preparation for an upcoming release of 0.20.0, where we need the extra-byte removal ( 🥲 ) as there are multiple script ids printed on newlines.

When you run it via the demo, you don't have that version (it's using 0.19.0) so it just incorrectly removes the final byte.

I think perhaps the best idea for now is to accept this PR, which reverts it to 0.19.0 behaviour, and then we will make this change again when the demo uses 0.20.0.

Thanks for finding this!

[noonio]

Approving; the code here was updated for 0.20.0 of hydra-node (which prints a list of scripts instead of a single one).

So we can just remove it entirely.

Thanks!