Respect PATHEXT when locating JS runtime on Windows (#15117)

Fixes #15043

Authored by: Grub4K

yt_dlp/utils/_utils.py

@@ -876,13 +876,19 @@ class Popen(subprocess.Popen):
             kwargs.setdefault('encoding', 'utf-8')
             kwargs.setdefault('errors', 'replace')
 
-        if shell and os.name == 'nt' and kwargs.get('executable') is None:
-            if not isinstance(args, str):
-                args = shell_quote(args, shell=True)
-            shell = False
-            # Set variable for `cmd.exe` newline escaping (see `utils.shell_quote`)
-            env['='] = '"^\n\n"'
-            args = f'{self.__comspec()} /Q /S /D /V:OFF /E:ON /C "{args}"'
+        if os.name == 'nt' and kwargs.get('executable') is None:
+            # Must apply shell escaping if we are trying to run a batch file
+            # These conditions should be very specific to limit impact
+            if not shell and isinstance(args, list) and args and args[0].lower().endswith(('.bat', '.cmd')):
+                shell = True
+
+            if shell:
+                if not isinstance(args, str):
+                    args = shell_quote(args, shell=True)
+                shell = False
+                # Set variable for `cmd.exe` newline escaping (see `utils.shell_quote`)
+                env['='] = '"^\n\n"'
+                args = f'{self.__comspec()} /Q /S /D /V:OFF /E:ON /C "{args}"'
 
         super().__init__(args, *remaining, env=env, shell=shell, **kwargs, startupinfo=self._startupinfo)