Python script under daemontools does not get signal 15

I have a python script which I want to run as a daemon under
daemontools. My program catches SIGINT and SIGALRM and when the
signals are received program exits.

When the program is run from command line and kill -1 <pid> and kill
-15 <pid> is signaled, the signal handler is run, which causes program
to exit, and corresponding logs are printed.

But when the program is run under daemontools, and svc -d
/service/myrogram is executed, the program neither exits nor logs are
printed.

I am using following run script to run the program under daemontools

#!/bin/sh
exec 2>&1
/usr/bin/python /home/test/sigtest.py

I am wondering why kill -15 <pid> works while svc -d /service/myrogram
does not seems to deliver the signal to the python program.

The python script I am working with is:

from pyudev import Context, Monitor, MonitorObserver
import signal, sys, time

def print_device_event(device):
    print ('New event - {0.action}: {0.device_path}'.format(device))

if __name__ == '__main__':
    context = Context()
    monitor = Monitor.from_netlink(context)
    observer = MonitorObserver(monitor, callback=print_device_event,
name='monitor-observer')
    print ("Processing started")
    observer.start()
    def handler(signum, frame):
        print("Received Signal: %d"%signum)
        observer.send_stop()
        print("Exiting.")
    signal.signal(signal.SIGTERM, handler)
    signal.signal(signal.SIGHUP, handler)

    try:
        while observer.is_alive():
            observer.join(timeout=1.0)
    except (KeyboardInterrupt, SystemExit):
        print("Caught KeyboardInterrupt, exiting")
        observer.send_stop()

Any help is much appreciated

Thanks and Regards,

Raj