#1940: make it possible to use curses.filter() before curses.initscr()

as the documentation says.
 (backport from rev. 60322)

Misc/NEWS

@@ -212,6 +212,9 @@ Library
 Extension Modules
 -----------------
 
+- #1940: make it possible to use curses.filter() before curses.initscr()
+  as the documentation says.
+
 - Fix a potential 'SystemError: NULL result without error' in _ctypes.
 
 - Prevent a segfault when a ctypes NULL function pointer is called.

Modules/_cursesmodule.c

@@ -1619,10 +1619,19 @@ NoArgTrueFalseFunction(has_colors)
 NoArgTrueFalseFunction(has_ic)
 NoArgTrueFalseFunction(has_il)
 NoArgTrueFalseFunction(isendwin)
-NoArgNoReturnVoidFunction(filter)
 NoArgNoReturnVoidFunction(flushinp)
 NoArgNoReturnVoidFunction(noqiflush)
 
+static PyObject *
+PyCurses_filter(PyObject *self)
+{
+  /* not checking for PyCursesInitialised here since filter() must
+     be called before initscr() */
+  filter();
+  Py_INCREF(Py_None);
+  return Py_None;
+}
+
 static PyObject *
 PyCurses_Color_Content(PyObject *self, PyObject *args)
 {