SIGINT not breaking loop with non-list function body

[Grisha Levit]

If an interactive shell line is just a single loop and the body of the loop
consists only of a function name, and the function body is not a list, ^C
does not cause the loop to break as it otherwise would.

$ f() { cat; }
$ while :; do f; done
^C

The code in wait_for() checks the values of loop_level and executing_list:

jobs.c:5095:55
-> 5095 if (signal_is_trapped (SIGINT) == 0 && (loop_level ||
(shell_compatibility_level > 32 && executing_list)))
   5096 ADDINTERRUPT;

but loop_level is reset by execute_function():

execute_cmd.c:5171:5
   5170 if (shell_compatibility_level > 43)
-> 5171 loop_level = 0;


This code in wait_for seems to be the only place where the value of
executing_list is tested, so maybe changing that variable to something like
executing_list_or_loop and adding in/decrements of it in the loop-related
execute_* functions would make sense.