feat: skip scripts that use "npx only-allow pnpm"

ref #2517
PR #2518

.changeset/mighty-keys-type.md

@@ -0,0 +1,5 @@
+---
+"@pnpm/lifecycle": minor
+---
+
+Don't execute lifecycle scripts that are meant to prevent the usage of npm or Yarn.

package.json

@@ -1,5 +1,6 @@
 {
   "scripts": {
+    "preinstall": "npx only-allow pnpm",
     "lint": "tslint --config tslint.json **/src/**/*.ts **/test/**/*.ts --exclude '**/node_modules/**'",
     "test-master": "pnpm run lint && pnpm run compile && run-p -r verdaccio test-pkgs-master",
     "test-pkgs-master": "cross-env PNPM_REGISTRY_MOCK_UPLINK=http://localhost:7348 pnpm run _test --no-sort --filter=./packages --filter=./privatePackages",

packages/lifecycle/src/runLifecycleHook.ts

@@ -32,6 +32,9 @@ export default async function runLifecycleHook (
   if (opts.args?.length && m.scripts?.[stage]) {
     m.scripts[stage] = `${m.scripts[stage]} ${opts.args.map((arg) => `"${arg}"`).join(' ')}`
   }
+  // This script is used to prevent the usage of npm or Yarn.
+  // It does nothing, when pnpm is used, so we may skip its execution.
+  if (m.scripts[stage] === 'npx only-allow pnpm') return
   if (opts.stdio !== 'inherit') {
     lifecycleLogger.debug({
       depPath: opts.depPath,