> Changes since v1:
> 
> - Fix commit title to follow "area: description" convention
>   ("refs: add 'preparing' phase to reference-transaction hook")
> - Correct phase names in documentation to past tense
>   ("committed", "aborted")
> - Fix the sentence about backwards compatibility with unknown phases
> - Update die() messages to identify the hook by full name and phase
>   ("ref updates rejected by the reference-transaction hook at its
>   preparing/prepared phase")
> - Consolidate author identity to eric.peijian@gmail.com
> - Add clarification in reply to the question about how to use the preparing
>   phase for write serialization

> Range-diff against v1:
> 1:  5f9f13a84d ! 1:  fb74f21d98 Add preparing state to reference-transaction hook
>     @@ Commit message
>          interfering with the locking state.
>      
>          This change is strictly speaking not backwards compatible. Existing hook
>     -    scripts that do not know to handle unknown phases handle the "preparing" state
>     -    string will encounter an unknown phase, and that might cause them to return an
>     -    error now. But the hook is considered to expose internal implementation details
>     +    scripts that do not know how to handle unknown phases may treat
>     +    'preparing' as an error and return non-zero.
>     +    But the hook is considered to expose internal implementation details
>          of how Git works, and as such we have been a bit more lenient with changing its
>          exact semantics, like for example in a8ae923f85 (refs: support symrefs in
>          'reference-transaction' hook, 2024-05-07).