All of our tgz archives named nnn.tgz extract to a directory named nnn, with the following two exceptions (tested on 4.1.8 only):

• mongodb-linux-arm64-enterprise-ubuntu1604-4.1.8.tgz extracts to mongodb-linux-aarch64-enterprise-ubuntu1604-4.1.8
• mongodb-linux-arm64-ubuntu1604-4.1.8.tgz extracts to mongodb-linux-aarch64-ubuntu1604-4.1.8

Haven't checked Ubuntu 18.04, but the issue is very likely to exist there as well.

I don't see anything obvious in evergreen.yml other than the use of push_arch (values are arm64-enterprise-ubuntu1604 and arm64-ubuntu1604. I'm guessing the aarch64 comes from doing scons dist.

I don't think this is a practical issue for anyone, just a deviation from all other platforms.