mac: BASIC_REPL asyncio then ctrl+c will break the readline on mac

[yihong0618]

Bug report

Bug description:

it very strange test linux and mac it only happend on mac

cc @kumaraditya303

➜  cpython git:(main) PYTHON_BASIC_REPL=1 ./python.exe -m asyncio
asyncio REPL 3.15.0a1+ (heads/main:d301587369, Oct 15 2025, 22:33:48) [Clang 17.0.0 (clang-1700.0.13.5)] on darwin
Use "await" directly instead of "asyncio.run()".
Type "help", "copyright", "credits" or "license" for more information.
>>> import asyncio
>>> ^C^[[A^[[A^[[A

>>> await asyncio.sleep(200)
^C^C^C^C

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

[yihong0618]

update:

1. the bug exists in 3.12, 3.13, 3.14, main
2. it is because mac use editline
3. type ctrl+c in it, it will break all ctrl+c after the first one

[yihong0618]

update

this diff can fix the error because the signal can not restore in editline
the root cause maybe in it

diff --git a/Modules/readline.c b/Modules/readline.c
index 630a687999..400e0468b0 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -1427,11 +1427,33 @@ setup_readline(readlinestate *mod_state)
 /* Wrapper around GNU readline that handles signals differently. */
 
 static char *completed_input_string;
+
+/* Ensure SIGINT is not blocked (macOS editline workaround) */
+static void
+unblock_sigint(void)
+{
+#ifdef HAVE_SIGACTION
+    sigset_t sigset;
+    if (sigprocmask(SIG_SETMASK, NULL, &sigset) == 0 &&
+        sigismember(&sigset, SIGINT)) {
+        sigset_t unblock;
+        sigemptyset(&unblock);
+        sigaddset(&unblock, SIGINT);
+        sigprocmask(SIG_UNBLOCK, &unblock, NULL);
+    }
+#endif
+}
+
 static void
 rlhandler(char *text)
 {
     completed_input_string = text;
     rl_callback_handler_remove();
+    /* On macOS editline, rl_callback_handler_remove() may block SIGINT.
+     * Unblock it so Ctrl+C works in subsequent input. */
+    if (using_libedit_emulation) {
+        unblock_sigint();
+    }
 }
 
 static char *