Wireless scan: signal only works in main thread

[noraj]

Right after launching the wireless scan:

[*] Start scanning network
[*] START AtEar-WIDS
/usr/share/atear
[2019-01-25 18:56:58,505] ERROR in app: Exception on /api/scanstatus [GET]
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "run.py", line 100, in scanstatus
    wids = Wireless_IDS(self.scan_iface)
  File "/usr/share/atear/module/wids.py", line 90, in __init__
    signal.signal(signal.SIGTERM, signal_handler)
ValueError: signal only works in main thread