`stage_bor_heimdall` commit partial progress if external `rwtx` is nil

[AskAlexSharov]

see example in another stages: useExternalTx := txc.Tx != nil

[stevemilk]

Hi Sir, I want help fix this issue but have a question: In stage_exec , external rwtx is defined as from kv.chainDB. It can be nil if noCommit==false, and that's why we use useExternalTx := txc.Tx != nil. However, instageBorHeimdall,external rwtx will definitely be created as a non-nil value by db.update() if no error thrown. Is this true? if true, no need to fix this.

[AskAlexSharov]

There are several places where stages are called. Some pass external rwtx, some are not.

“integration” usually doesn’t.

kv.RwTx and kv.RwDB are 2 different objects.

[stevemilk]

draft a pr #12097 to enable stage_bor_heimdall to commit partial progress, is this as expected?