gh-109945 fix incorrect reference management of string

Signed-off-by: Nigel Jones <jonesn@uk.ibm.com>

Author: planetf1

Modules/_ssl.c

@@ -4401,12 +4401,13 @@ _ssl__SSLContext_set_ecdh_curve(PySSLContext *self, PyObject *name)
     EC_KEY_free(key);
 #else
     int res = SSL_CTX_set1_groups_list(self->ctx, PyBytes_AS_STRING(name_bytes));
-    Py_DECREF(name_bytes);
     if (!res) {
         PyErr_Format(PyExc_ValueError,"unknown elliptic curves %R", name_bytes);
+        Py_DECREF(name_bytes);
         _setSSLError(get_state_ctx(self), NULL, 0, __FILE__, __LINE__);
         return NULL;
     }
+    Py_DECREF(name_bytes);
 #endif
     Py_RETURN_NONE;
 }