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

The 2.2-develop branch contains the 2.2.1-dev Magento 2 version:

The develop branch contains the 2.3.0-dev Magento 2 version:

See also:

• The develop and 2.3-develop git branches now contain an identical code
• How to clone the Magento 2.3 git branch (develop or 2.3-develop)?