tl;dr: the D install script is now able to install a specific version of DUB.

./install.sh dmd-2.072.2,dub
./install.sh ldc-1.10.0,dub

This is mostly useful if you want to test an old version of a DMD or LDC on a CI, but want to take advantage of all the stability fixes in dub and thus use the latest dub.
The install.sh script is used on Travis too, so this will now work on Travis too:

d: dmd-2.072.2,dub


But of course you can select a specific version too:

./install.sh dmd-2.072.2,dub.1.7.2



Learn more about the install script: https://dlang.org/install

Learn more about using D on Travis: https://docs.travis-ci.com/user/languages/d/

More details about this change: https://github.com/dlang/installer/pull/301