diff --git a/.buildkite/commands/checkout-release-branch.sh b/.buildkite/commands/checkout-release-branch.sh
deleted file mode 100755
index 0650af0d1d41..000000000000
--- a/.buildkite/commands/checkout-release-branch.sh
+++ /dev/null
@@ -1,38 +0,0 @@
-#!/bin/bash -eu
-
-# Checks out the `release/*` branch for a given release version.
-#
-# Usage: checkout-release-branch.sh [<RELEASE_VERSION>]
-#
-# The release version is taken from the first of these that is set and non-empty:
-#  1. the first argument
-#  2. the `RELEASE_VERSION` environment variable
-#  3. the `release/*` branch the build is running on, via `BUILDKITE_BRANCH`
-#
-# Buildkite, by default, checks out a specific commit, ending up in a detached HEAD state.
-# But some release steps need to be on the `release/*` branch instead, namely:
-#  - when a `release-pipelines/*.yml` needs to `git push` to the `release/*` branch (for version bumps)
-#  - when a job `pipeline upload`'d by such a pipeline builds from that branch, so that the build
-#    includes the commit that the version bump just added.
-
-echo "--- :git: Checkout Release Branch"
-
-RELEASE_VERSION="${1:-${RELEASE_VERSION:-}}"
-
-if [[ -z "$RELEASE_VERSION" && "${BUILDKITE_BRANCH:-}" =~ ^release/ ]]; then
-  RELEASE_VERSION="${BUILDKITE_BRANCH#release/}"
-fi
-
-if [[ -z "$RELEASE_VERSION" ]]; then
-  echo "Error: no release version. Pass it as \$1, set RELEASE_VERSION, or run on a release/* branch." >&2
-  exit 1
-fi
-
-BRANCH_NAME="release/${RELEASE_VERSION}"
-git fetch origin "$BRANCH_NAME"
-git checkout "$BRANCH_NAME"
-# Buildkite can reuse a working copy where "$BRANCH_NAME" was left at a different commit by a previous job,
-# so force the local branch to the fetched commit.
-#  - `reset --hard` rather than `git pull`, to avoid merging if the two diverged
-#  - `FETCH_HEAD` rather than `origin/$BRANCH_NAME`, which `git fetch <branch>` only updates opportunistically.
-git reset --hard FETCH_HEAD
diff --git a/.buildkite/commands/complete-code-freeze.sh b/.buildkite/commands/complete-code-freeze.sh
index 9297d9e4d298..5f3654e43274 100755
--- a/.buildkite/commands/complete-code-freeze.sh
+++ b/.buildkite/commands/complete-code-freeze.sh
@@ -10,7 +10,7 @@ fi
 echo '--- :robot_face: Use bot for Git operations'
 source use-bot-for-git
 
-.buildkite/commands/checkout-release-branch.sh "$RELEASE_NUMBER"
+checkout_release_branch "$RELEASE_NUMBER"
 
 "$(dirname "${BASH_SOURCE[0]}")/shared-set-up.sh"
 
diff --git a/.buildkite/commands/finalize-hotfix.sh b/.buildkite/commands/finalize-hotfix.sh
index cb3be53d1d66..e69f6e6a137a 100755
--- a/.buildkite/commands/finalize-hotfix.sh
+++ b/.buildkite/commands/finalize-hotfix.sh
@@ -10,7 +10,7 @@ fi
 echo '--- :robot_face: Use bot for Git operations'
 source use-bot-for-git
 
-.buildkite/commands/checkout-release-branch.sh "$RELEASE_NUMBER"
+checkout_release_branch "$RELEASE_NUMBER"
 
 echo '--- :ruby: Setup Ruby tools'
 install_gems
diff --git a/.buildkite/commands/finalize-release.sh b/.buildkite/commands/finalize-release.sh
index bbba37e01b8d..921e50761041 100755
--- a/.buildkite/commands/finalize-release.sh
+++ b/.buildkite/commands/finalize-release.sh
@@ -10,7 +10,7 @@ fi
 echo '--- :robot_face: Use bot for Git operations'
 source use-bot-for-git
 
-.buildkite/commands/checkout-release-branch.sh "$RELEASE_NUMBER"
+checkout_release_branch "$RELEASE_NUMBER"
 
 echo '--- :ruby: Setup Ruby tools'
 install_gems
diff --git a/.buildkite/release-builds.yml b/.buildkite/release-builds.yml
index 1839174c967f..99338e8aab87 100644
--- a/.buildkite/release-builds.yml
+++ b/.buildkite/release-builds.yml
@@ -9,7 +9,7 @@ steps:
 
   - label: ":wordpress: :testflight: WordPress Release Build (App Store Connect)"
     command: |
-      .buildkite/commands/checkout-release-branch.sh "$RELEASE_VERSION"
+      checkout_release_branch "$RELEASE_VERSION"
       .buildkite/commands/release-build-wordpress.sh $IS_BETA_RELEASE
     plugins: [$CI_TOOLKIT_PLUGIN]
     notify:
@@ -21,7 +21,7 @@ steps:
 
   - label: ":jetpack: :testflight: Jetpack Release Build (App Store Connect)"
     command: |
-      .buildkite/commands/checkout-release-branch.sh "$RELEASE_VERSION"
+      checkout_release_branch "$RELEASE_VERSION"
       .buildkite/commands/release-build-jetpack.sh
     plugins: [$CI_TOOLKIT_PLUGIN]
     notify:
diff --git a/.buildkite/release-pipelines/publish-release.yml b/.buildkite/release-pipelines/publish-release.yml
index 024c3f616f90..71e92ce303e5 100644
--- a/.buildkite/release-pipelines/publish-release.yml
+++ b/.buildkite/release-pipelines/publish-release.yml
@@ -14,7 +14,7 @@ steps:
       echo '--- :robot_face: Use bot for Git operations'
       source use-bot-for-git
 
-      .buildkite/commands/checkout-release-branch.sh "$RELEASE_VERSION"
+      checkout_release_branch "$RELEASE_VERSION"
 
       echo '--- :ruby: Setup Ruby tools'
       install_gems
diff --git a/.buildkite/shared-pipeline-vars b/.buildkite/shared-pipeline-vars
index ef632b72f9df..a582ccd52c0a 100755
--- a/.buildkite/shared-pipeline-vars
+++ b/.buildkite/shared-pipeline-vars
@@ -5,7 +5,7 @@
 
 # The ~> modifier is not currently used, but we check for it just in case
 XCODE_VERSION=$(sed -E 's/^~> ?//' .xcode-version)
-CI_TOOLKIT_PLUGIN_VERSION="6.1.1"
+CI_TOOLKIT_PLUGIN_VERSION="6.3.0"
 TEST_COLLECTOR_PLUGIN_VERSION="1.11.0"
 
 export IMAGE_ID="xcode-$XCODE_VERSION"