The Telegraph reports

The above will only apply to travelers who test negative for the coronavirus, in which I would assume testing is done at the airport upon arrival - as most countries are doing now.

The idea here is to ease the burden on travelers, though the whole 7-day, 10-day, 14-day quarantine debate is still very much up in the air at this point since it differs from case-to-case. But that is just the general rule of thumb in a monkey see, monkey do world.