WindowsError.str should display the windows error code,
not the posix error code; with test.
Fixes #1576174.

Will backport to release25-maint.
diff --git a/Misc/NEWS b/Misc/NEWS
index ab3bf3f..b9b9883 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,9 @@
 Core and builtins
 -----------------
 
+- Bug #1576174: WindowsError now displays the windows error code
+  again, no longer the posix error code.
+
 - Patch #1549049: Support long values in structmember, issue warnings
   if the assigned value for structmember fields gets truncated.