Merge rust-bitcoin/rust-bitcoin#2627: Introduce new one ACK carve-out rule

9b70c65f5d Introduce new one-ack carve out rule (Tobin C. Harding)
42d02fbd66 Merge Refactor and One ACK carve outs (Tobin C. Harding)
ebf5b670d4 Update test script mention (Tobin C. Harding)

Pull request description:

  Update merge carve-out policy and introduce new rule.

  - Patch 1: Fix stale test script mention
  - Patch 2: Merge current carve-outs into a single carve-out with multiple rules
  - Patch 3: Introduce new carve-out rule

  From patch 3:
  ```
      Introduce new one-ack carve out rule

      Our merge process is being artificially slowed down because of a
      combination of:

      - Using merge-commit merging means PRs often have to be rebased with no
        changes but a different merge base (and force pushed).
      - Trivial changes, like fixing nits, are often force pushed also.
      - Force pushes invalidate ACKs
      - Our devs are spread around the world working at different times

      What this means is trivial force pushes often cause multi day delays in
      merging. To try and alleviate this problem introduce an additional rule
      to the One ACK carve-out so that Andrew can merge PRs that have
      previously been ack'ed by another dev and have only minimal changes.
      The definition of "trivial" is subjective which introduces a burden on
      Andrew to not merge stuff willy-nilly but also allows simple changes to
      the original PR (eg fixed nits that the original reviewer suggested).
  ```

ACKs for top commit:
  apoelstra:
    ACK 9b70c65f5d confirmed via range-diff that the commit everyone ACKed and this one differ only in `as` vs `has`

Tree-SHA512: 41898e71e013ac70e41bb4624ce5e5055dc3e7a405dd73d3988f5b02ece104d7fad746203ce8d26a6a33f98b745010fc39e9a4bddb9bcf22267c942a4dac2028

CONTRIBUTING.md

@@ -150,32 +150,38 @@ Current list of the project maintainers:
 - [Riccardo Casatta](https://github.com/RCasatta)
 - [Tobin Harding](https://github.com/tcharding)
 
-#### Refactor carve-out
+#### One ACK carve-out
 
 The repository is going through heavy refactoring and "trivial" API redesign
 (eg, rename `Foo::empty` to `Foo::new`) as we push towards API stabilization. As
 such reviewers are either bored or overloaded with notifications, hence we have
 created a carve out to the 2-ACK rule.
 
-A PR may be considered for merge if it has a single ACK and has sat open for at
-least two weeks with no comments, questions, or NACKs.
-
-#### One ACK carve-out
-
 We reserve the right to merge PRs with a single ACK [0], at any time, if they match
 any of the following conditions:
 
-1. PR only touches CI i.e, only changes any of the `test.sh` scripts and/or
+0. PR has a single ACK and has sat open for at least two weeks with no comments,
+   questions, or NACKs.
+1. PR only touches CI i.e, only changes any of the test scripts and/or
    stuff in `.github/workflows`.
 2. Non-content changing documentation fixes i.e., grammar/typos, spelling, full
    stops, capital letters. Any change with more substance must still get two
    ACKs.
 3. Code moves that do not change the API e.g., moving error types to a private
    submodule and re-exporting them from the original module. Must not include
-   any code changes except to import paths. This rule is more restrictive than
-   the refactor carve-out. It requires absolutely no change to the public API.
+   any code changes except to import paths. Requires absolutely no change to the
+   public API.
+4. PR has previously had two ACKs, had minimal changes, and gets a single ACK
+   from Andrew. This call is subjective, gives extra privileges, but also
+   requires extra responsibility/accountability (including running a bunch
+   of local CI checks before merging) [1].
+
+
 
 [0] - Obviously author and ACK'er must not be the same person.
+[1] - The aim is to reduce the burden of re-ACK'ing trivial changes and also
+      alleviate the problem of devs spread around the world in different timezones.
+
 
 ## Coding conventions