Hi Adam, funnily enough someone else asked me exactly the same question recently. You can call your versions anything you like, so there's no problem with versioning a build as 1.7.1 if you already have 1.8.0. The part that always has to increase is the build number (known as version code on Android).

So if your issue is with 1.7.0 build 134, and you already have, say 1.8.0 build 202 in internal test, you could create your hotfix as 1.7.1 build 203.

Hope that helps.