How to clone the Magento 2.3 git branch («develop» or «2.3-develop»)?

git clone -b develop https://github.com/magento/magento2 .

or:

git clone -b 2.3-develop https://github.com/magento/magento2 .

It is the same, because the develop and 2.3-develop git branches now contain an identical code.

See also:

• Magento 2 team has changed the default Git branch from develop to 2.2-develop