Backport of Ryo fix for a wallet caching bug

[fireice-uk]

xref ryo-currency/ryo-currency#86

[fireice-uk]

Note, please see the other commits in the xref'ed pr. I didn't include them because our fork selection system works differently to yours.

[moneromooo-monero]

Looks ok, please use a sensible commit message though (eg, "node_rpc_proxy: fix fork earliest height caching" or so).

[fireice-uk]

Changed. Please note my previous message, you also need to either:

• Fix get_earliest_ideal_height_for_version to return an invalid height for unknown forks as per this commit ryo-currency/ryo-currency@12bad0a

• Cache enabled separately and re-combine the result post-caching.

As this is more of high-level "where do you want to go?" decision I didn't include it. Let me know if you want to go 12bad0a route and I can back port that code too.

[moneromooo-monero]

Can you explain why ? If the "unknown" fork is higher than the highest known one, we return max value and never use those rules. If it's between two known ones, we use it when we switch to the next one, so that looks OK to me at first glance.

[fireice-uk]

Problem is that get_earliest_ideal_height_for_version will return 1546000 for any input >= 7 in your case. As long as that behaviour is expected then you can get away with just this patch.

In our case we have different features enabled on different versions for the testnet and mainnet so this is how it triggered a secondary bug (we assigned bulletproofs to a disabled v255).

[moneromooo-monero]

OK. It should currently return max uint64_t by my reading, and it changed a few months ago to support "jumps" in versions as aeon was doing that and this got backported. We'll do with just what you PRed, thanks.