merge 3.3 (#20374)

diff --cc Modules/readline.c
index ed83818b7c9f748a9fb307a91c9590947e146ae8,4ee17a91cd977dd96ffb3adda7cbe92da0151032..02521aaca4bb4e9166c4b92c1a4e850a635f2a9f
--- 1/Modules/readline.c
--- 2/Modules/readline.c
+++ b/Modules/readline.c
@@@ -935,12 -877,8 +935,12 @@@ on_completion(const char *text, int sta
   * before calling the normal completer */
  
  static char **
- flex_complete(char *text, int start, int end)
+ flex_complete(const char *text, int start, int end)
  {
 +    char **result;
 +#ifdef WITH_THREAD
 +    PyGILState_STATE gilstate = PyGILState_Ensure();
 +#endif
  #ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
      rl_completion_append_character ='\0';
  #endif