fix #1965 / win / users() / critical: Py_INCREF(Py_None) before setti…

…ng None object in C

Signed-off-by: Giampaolo Rodola <g.rodola@gmail.com>

HISTORY.rst

@@ -33,6 +33,8 @@ XXXX-XX-XX
   by Xuehai Pan)
 - 1953_: [Windows] disk_partitions() crashes due to insufficient buffer len.
   (patch by MaWe2019)
+- 1965_: [Windows] fix "Fatal Python error: deallocating None" when calling
+  psutil.users() multiple times.
 - 1991_: process_iter() can raise TypeError if invoked from multiple threads
   (not thread-safe).
 

psutil/_psutil_windows.c

@@ -1252,6 +1252,7 @@ psutil_users(PyObject *self, PyObject *args) {
                 goto error;
         }
         else {
+            Py_INCREF(Py_None);
             py_address = Py_None;
         }