Update,

I pulled out the sensor the bulb was screwed into and checked the
wires again.

Open between all, thought it was fixed.

Hooked circuit back up to switch in house and turned on.

Immediately blew breaker.

With the breaker off and the wires to the switch still connected to
pole,(in Junction box in cellar), I tested circuit again and black to
copper was open but white to copper now had a reading back up the
circuit to the switch.

I took a extension cord and put the wires from the pole in it and
plugged it in and the light came on and worked fine.

I must also mention that the switch for this thing gets it's power
from a row of 4 switches near my front door.

There are 4 switches the pole one being the last in line.

They are wired as follows,

The switches all have the black wire to them and the bare copper then
in the switch box the white wires are all twisted together, none of
the white goes to the switches.

As far as I can tell, even though it seems unlikely is the wires from
the pole switch to the cellar jct box must be shorted.

Note also I can turn the pole switch on and off as long as it is
disconnected from the pole light wires in the JCT box in the cellar
with no problem.