gh-000: Add missing stacklevel to warnings.warn() in subprocess.Popen

Both warnings.warn() calls in Popen.__init__ (one on POSIX for
pass_fds overriding close_fds, one on Windows for handle_list
overriding close_fds) were missing stacklevel=2.

Without stacklevel=2, the warning points to an internal line in
subprocess.py rather than the caller's Popen() invocation, making
it harder for users to locate the source of the warning in their
own code.

Author: stef41

Lib/subprocess.py

@@ -912,7 +912,7 @@ def __init__(self, args, bufsize=-1, executable=None,
         else:
             # POSIX
             if pass_fds and not close_fds:
-                warnings.warn("pass_fds overriding close_fds.", RuntimeWarning)
+                warnings.warn("pass_fds overriding close_fds.", RuntimeWarning, stacklevel=2)
                 close_fds = True
             if startupinfo is not None:
                 raise ValueError("startupinfo is only supported on Windows "
@@ -1567,7 +1567,8 @@ def _execute_child(self, args, executable, preexec_fn, close_fds,
                 if handle_list:
                     if not close_fds:
                         warnings.warn("startupinfo.lpAttributeList['handle_list'] "
-                                      "overriding close_fds", RuntimeWarning)
+                                      "overriding close_fds", RuntimeWarning,
+                                      stacklevel=2)
 
                     # When using the handle_list we always request to inherit
                     # handles but the only handles that will be inherited are