eth/vm/state: recurse collect_touched_accounts() always, unless computation had error.

Previously, "nested" computations would be recursed into even if
they had an error; whereas "origin" computation would be recursed into
on success only.

This commit effectively makes so that "nested" comp-ns will be recursed
into only if they are successful (that is, same logic as for "origin"
comp-n).

The rest of the changes are comments, heredoc brush-ups, and similar
fluff from the debugging session.

Author: veox

eth/vm/forks/spurious_dragon/_utils.py

@@ -17,15 +17,18 @@
 @to_set
 def collect_touched_accounts(computation: BaseComputation) -> Iterable[bytes]:
     """
-    Collect all of the accounts that *may* need to be deleted based on EIP161:
+    Collect all of the accounts that *may* need to be deleted based on
+    `EIP-161 <https://eips.ethereum.org/EIPS/eip-161>`_.
 
-    https://github.com/ethereum/EIPs/blob/master/EIPS/eip-161.md
+    Checking whether they *do* need to be deleted happens in the caller.
 
-    also see: https://github.com/ethereum/EIPs/issues/716
+    See also: https://github.com/ethereum/EIPs/issues/716
     """
+    # collect the coinbase account if it was touched via zero-fee transfer
     if computation.is_origin_computation and computation.transaction_context.gas_price == 0:
         yield computation.state.coinbase
 
+    # collect those explicitly marked for deletion ("beneficiary" is of SELFDESTRUCT)
     for beneficiary in sorted(set(computation.accounts_to_delete.values())):
         if computation.is_error and computation.is_origin_computation:
             # Special case to account for geth+parity bug
@@ -36,6 +39,7 @@ def collect_touched_accounts(computation: BaseComputation) -> Iterable[bytes]:
         else:
             yield beneficiary
 
+    # collect account directly addressed
     if computation.msg.to != constants.CREATE_CONTRACT_ADDRESS:
         if computation.is_error and computation.is_origin_computation:
             # Special case to account for geth+parity bug
@@ -45,6 +49,7 @@ def collect_touched_accounts(computation: BaseComputation) -> Iterable[bytes]:
         else:
             yield computation.msg.to
 
-    if not computation.is_origin_computation or not computation.is_error:
+    # recurse into nested computations if this one was successful
+    if not computation.is_error:
         for child in computation.children:
             yield from collect_touched_accounts(child)

tests/conftest.py

@@ -1,5 +1,3 @@
-# from eth._utils.logging import DEBUG2_LEVEL_NUM
-
 import pytest
 
 from eth_utils import (
@@ -31,7 +29,7 @@
 import datetime
 import logging
 import os
-from eth.tools.logging import TRACE_LEVEL_NUM
+from eth.tools.logging import DEBUG2_LEVEL_NUM
 
 @pytest.yield_fixture(autouse=True)
 def _file_logging(request):