Tie library build metadata specifically to the last commit in its dir…

…ectory

packages/library/webpack.config.js

@@ -111,7 +111,7 @@ module.exports = (env, argv) => {
       new webpack.DefinePlugin({
         BUILD_FLAVOR: JSON.stringify(target),
         BUILD_COMMIT: JSON.stringify(
-          shell.exec('git rev-parse HEAD', { silent: true }).trim()
+          shell.exec('git rev-list -1 HEAD -- .', { silent: true }).trim()
         ),
       }),
     ],