build: avoid WSL interop flake when preparing Windows CI environment

For our native Windows tests (verifying `ng` CLI outside WSL), we
currently build the test binaries inside WSL, leveraging bazel remote
execution.

The scripts involved in moving the built binaries to outside WSL rarely
flake due to a WSL interop bug when we invoke Windows commands from inside
WSL (which is an untypical thing to do; but a needed trick given some WSL limitation).

This commit tries to stabilize/avoid this flake by retrying if we
recognize this.

(cherry picked from commit 54c561a)

Author: devversion

scripts/windows-testing/convert-symlinks.mjs

@@ -119,10 +119,22 @@ async function transformDir(p) {
   }
 }
 
-function exec(cmd) {
+function exec(cmd, maxRetries = 2) {
   return new Promise((resolve, reject) => {
     childProcess.exec(cmd, { cwd: rootDir }, (error) => {
       if (error !== null) {
+        // Windows command spawned within WSL (which is untypical) seem to be flaky rarely.
+        // This logic tries to make it fully stable by re-trying if this surfaces:
+        // See: https://github.com/microsoft/WSL/issues/8677.
+        if (
+          maxRetries > 0 &&
+          error.stderr !== undefined &&
+          error.stderr.includes(`accept4 failed 110`)
+        ) {
+          resolve(exec(cmd, maxRetries - 1));
+          return;
+        }
+
         reject(error);
       } else {
         resolve();