calling test contract from within test contract makes the proof fail

prob related: https://github.com/runtimeverification/evm-semantics/issues/1691

when writing a test case such as:

function test_delegate() public {                                                         
    address(this).delegatecall(abi.encodeWithSignature("transfer(address,uint256)", address(10987654321), 500));                                                                        
}                                                                                         

the proof proving will fail.

$ kevm foundry-prove --test AssertTest.test_delegate

ERROR 2023-05-24 11:27:03,082 kevm_pyk.utils - Proof failed: AssertTest.test_delegate
PROOF FAILED: AssertTest.test_delegate

The kcfg-viewer gives us some more insight on the issue,

kevm foundry-kcfg-viewer AssertTest.test_delegate

@anvacaru thought that the reason is that the ACCT that is "from" is a symbolic Int which is not in the active accounts cell and makes the proof fail.

Start by reproducing AssertTest.test_delegate with kevm foundry-prove --test AssertTest.test_delegate, then inspect the resulting state in kevm foundry-kcfg-viewer AssertTest.test_delegate. Investigate the reported symbolic ACCT and active accounts behavior; done means the nested delegatecall test proof completes successfully.