[3.10] gh-100776: Fix misleading default value in help(input) (GH-100788) (#100842)

(cherry picked from commit a214188)

Co-authored-by: Shantanu <[email protected]>

Author: hauntsaninja

Misc/NEWS.d/next/Core and Builtins/2023-01-06-02-02-11.gh-issue-100776.pP8xux.rst

@@ -0,0 +1 @@
+Fix misleading default value in :func:`input`'s ``__text_signature__``.

Python/bltinmodule.c

@@ -2034,7 +2034,7 @@ flush: whether to forcibly flush the stream.");
 /*[clinic input]
 input as builtin_input
 
-    prompt: object(c_default="NULL") = None
+    prompt: object(c_default="NULL") = ""
     /
 
 Read a string from standard input.  The trailing newline is stripped.
@@ -2048,7 +2048,7 @@ On *nix systems, readline is used if available.
 
 static PyObject *
 builtin_input_impl(PyObject *module, PyObject *prompt)
-/*[clinic end generated code: output=83db5a191e7a0d60 input=5e8bb70c2908fe3c]*/
+/*[clinic end generated code: output=83db5a191e7a0d60 input=159c46d4ae40977e]*/
 {
     PyObject *fin = _PySys_GetObjectId(&PyId_stdin);
     PyObject *fout = _PySys_GetObjectId(&PyId_stdout);