learning thermostat wiring, existing thermostat ob and w are on same wire. Do I need a jumper ?

[Houptee]

No jumper wires needed
The Nest Thermostat does not use jumper wires, it will automatically jump terminals for you. Do not connect
jumper wires to the Nest Thermostat. Before removing any wires from the old thermostat, including jumper
wires, take a picture of the existing wiring configuration in case you or the homeowner need to reinstall it.