Issue #5179: Fixed subprocess handle leak on failure on windows.
diff --git a/PC/_subprocess.c b/PC/_subprocess.c
index f2c6b92..bb240e1 100644
--- a/PC/_subprocess.c
+++ b/PC/_subprocess.c
@@ -87,7 +87,7 @@
 
 	handle = self->handle;
 
-	self->handle = NULL;
+	self->handle = INVALID_HANDLE_VALUE;
 
 	/* note: return the current handle, as an integer */
 	return HANDLE_TO_PYNUM(handle);