UpgradeSoulGasToken.s.sol: get impl correctly

[blockchaindevsh]

The Proxy.implementation() method can only be called from ProxyAdmin, otherwise will revert since there's no such method in the implementation contract.

UPDATE

This PR also ensures that sgt owner is not changed during the upgrade with 1f2f2c9.

[dajuguan]

How can we test it before deploying? Should we deploy it on the devnet first?

[blockchaindevsh]

How can we test it before deploying? Should we deploy it on the devnet first?

There's already a checkOutput() method, no transaction will be sent if the check fails.

[dajuguan]

Is it feasible to list the pre- and post-condition checks in the contracts to be deployed, so it will be easier for reviewers to understand what's going on?

[blockchaindevsh]

Is it feasible to list the pre- and post-condition checks in the contracts to be deployed, so it will be easier for reviewers to understand what's going on?

Don't quite understand, could you provide an example?

[dajuguan]

In this PR:
Precondition:

• only proxyAdmin can call

Postcondition:

• soulGasToken.name() == "SoulQKC"
• soulGasToken.symbol() == "SoulQKC"
• soulGasToken.owner == preOwner

[blockchaindevsh]

In this PR: Precondition:

• only proxyAdmin can call

Postcondition:

• soulGasToken.name() == "SoulQKC"
• soulGasToken.symbol() == "SoulQKC"
• soulGasToken.owner == preOwner

I can understand the Postcondition part, what do you want to do with the Precondition part?

[dajuguan]

For now, the only thing about Precondition I can think of is related to permissions. It's just an example

[dajuguan]

Nice!