How to clone Greg Kroah-Hartman's stagingtree repository for the Linux kernel?

I am using git to try and clone Greg Kroah-Hartman’s staging tree repository by using following command.

$ git clone -b staging-next git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git

However, I keep getting this error:

Cloning into 'staging'...
fatal: unable to connect to git.kernel.org:
git.kernel.org[0: 198.145.20.140]: errno=Connection refused
git.kernel.org[1: 199.204.44.194]: errno=Connection refused
git.kernel.org[2: 149.20.4.72]: errno=Connection refused
git.kernel.org[3: 2620:3:c000:a:0:1991:8:25]: errno=Network is unreachable
git.kernel.org[4: 2001:4f8:1:10:0:1991:8:25]: errno=Network is unreachable

What is the correct git command line to use?

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