Check for existence of .bin dir in pnp dependencies before adding t…

…o `PATH`. (#6711)

* Check PnP dep has `.bin` dir before adding to `PATH`

* Update CHANGELOG

* Update CHANGELOG.md

CHANGELOG.md

@@ -12,6 +12,10 @@ Please add one entry in this file for each change in Yarn's behavior. Use the sa
 
   [#6682](https://github.com/yarnpkg/yarn/pull/6682) - [**Maël Nison**](https://twitter.com/arcanis)
 
+- Decreases the size of the generated `$PATH` environment variable for a better Windows support
+
+  [#6683](https://github.com/yarnpkg/yarn/issues/6683) - [**Rowan Lonsdale**](https://github.com/hWorblehat)
+
 ## 1.12.3
 
 **Important:** This release contains a cache bump. It will cause the very first install following the upgrade to take slightly more time, especially if you don't use the [Offline Mirror](https://yarnpkg.com/blog/2016/11/24/offline-mirror/) feature. After that everything will be back to normal.

src/util/execute-lifecycle-script.js

@@ -217,7 +217,10 @@ export async function makeEnv(
         continue;
       }
 
-      pathParts.unshift(`${dependencyInformation.packageLocation}/.bin`);
+      const binFolder = `${dependencyInformation.packageLocation}/.bin`;
+      if (await fs.exists(binFolder)) {
+        pathParts.unshift(binFolder);
+      }
     }
 
     // Note that NODE_OPTIONS doesn't support any style of quoting its arguments at the moment