Issue 5913 - call correct npm executable on Win

ensure_dependencies.py

Index: ensure_dependencies.py
diff --git a/ensure_dependencies.py b/ensure_dependencies.py
index 1cbbf09522eef68283123f634370064352ec49f1..2e7013da39ee3d207f89cbc7b0a0c0117461bc17 100755
--- a/ensure_dependencies.py
+++ b/ensure_dependencies.py
@@ -278,7 +278,16 @@ def resolve_npm_dependencies(target, vcs):
         lockfile_path = os.path.join(target, NPM_LOCKFILE)
         open(lockfile_path, 'a').close()
 
-        cmd = ['npm', 'install', '--only=production', '--loglevel=warn',
+        if os.name == 'nt':
+            # Windows' CreateProcess() (called by subprocess.Popen()) only
+            # resolves executables ending in .exe. The windows installation of
+            # Node.js only provides a npm.cmd, which is executable but won't
+            # be recognized as such by CreateProcess().
+            npm_exec = 'npm.cmd'
+        else:
+            npm_exec = 'npm'
+
+        cmd = [npm_exec, 'install', '--only=production', '--loglevel=warn',
                '--no-package-lock', '--no-optional']
         subprocess.check_output(cmd, cwd=target)