workflows/check-by-name.yml: Switch to new separate repo

The nixpkgs-check-by-name tooling is [being moved](https://github.com/NixOS/nixpkgs/issues/286559#issuecomment-2000466124)
to a [separate repo](https://github.com/NixOS/nixpkgs-check-by-name).

This commit updates Nixpkgs CI to use it instead of the tree inside
Nixpkgs

No changes have been made to the tooling locally since it was moved:
- [Exported history](https://github.com/NixOS/nixpkgs/commits/55bf02190ee57fcf83490fd7b6bf7834e28c9c86/pkgs/test/nixpkgs-check-by-name)
- [Imported history](https://github.com/NixOS/nixpkgs-check-by-name/commits/d579e1821d56c79fd90dab34b991cc7bdab7a5c6/)

1 files changed, 73 insertions, 0 deletions

diff --git a/pkgs/test/check-by-name/run-local.sh b/pkgs/test/check-by-name/run-local.sh
new file mode 100755
index 0000000000000..b1b662046bf39
--- /dev/null
+++ b/pkgs/test/check-by-name/run-local.sh
@@ -0,0 +1,73 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p jq
+
+set -o pipefail -o errexit -o nounset
+
+trace() { echo >&2 "$@"; }
+
+tmp=$(mktemp -d)
+cleanup() {
+    # Don't exit early if anything fails to cleanup
+    set +o errexit
+
+    trace -n "Cleaning up.. "
+
+    [[ -e "$tmp/base" ]] && git worktree remove --force "$tmp/base"
+    [[ -e "$tmp/merged" ]] && git worktree remove --force "$tmp/merged"
+
+    rm -rf "$tmp"
+
+    trace "Done"
+}
+trap cleanup exit
+
+
+repo=https://github.com/NixOS/nixpkgs.git
+
+if (( $# != 0 )); then
+    baseBranch=$1
+    shift
+else
+    trace "Usage: $0 BASE_BRANCH [REPOSITORY]"
+    trace "BASE_BRANCH: The base branch to use, e.g. master or release-23.11"
+    trace "REPOSITORY: The repository to fetch the base branch from, defaults to $repo"
+    exit 1
+fi
+
+if (( $# != 0 )); then
+    repo=$1
+    shift
+fi
+
+if [[ -n "$(git status --porcelain)" ]]; then
+    trace -e "\e[33mWarning: Dirty tree, uncommitted changes won't be taken into account\e[0m"
+fi
+headSha=$(git rev-parse HEAD)
+trace -e "Using HEAD commit \e[34m$headSha\e[0m"
+
+trace -n "Creating Git worktree for the HEAD commit in $tmp/merged.. "
+git worktree add --detach -q "$tmp/merged" HEAD
+trace "Done"
+
+trace -n "Fetching base branch $baseBranch to compare against.. "
+git fetch -q "$repo" refs/heads/"$baseBranch"
+baseSha=$(git rev-parse FETCH_HEAD)
+trace -e "\e[34m$baseSha\e[0m"
+
+trace -n "Creating Git worktree for the base branch in $tmp/base.. "
+git worktree add -q "$tmp/base" "$baseSha"
+trace "Done"
+
+trace -n "Merging base branch into the HEAD commit in $tmp/merged.. "
+git -C "$tmp/merged" merge -q --no-edit "$baseSha"
+trace -e "\e[34m$(git -C "$tmp/merged" rev-parse HEAD)\e[0m"
+
+trace -n "Reading pinned nixpkgs-check-by-name version from pinned-version.txt.. "
+toolVersion=$(<"$tmp/merged/pkgs/test/check-by-name/pinned-version.txt")
+trace -e "\e[34m$toolVersion\e[0m"
+
+trace -n "Building tool.. "
+nix-build https://github.com/NixOS/nixpkgs-check-by-name/tarball/"$toolVersion" -o "$tmp/tool" -A build
+
+trace "Running nixpkgs-check-by-name.."
+"$tmp/tool/bin/nixpkgs-check-by-name" --base "$tmp/base" "$tmp/merged"