Are you having issues installing ReSharper in the last few days? Does the ReSharper installer complain that it doesn’t find any zones exactly matching 15.something?
If this is what you’re seeing, then get ReSharper Ultimate 2017.1.3. Looks like that the latest Visual Studio 2017 Preview (15.3) has changed its internal versioning, which affected stable Visual Studio versions installed on the same machine, which ReSharper had no way of being aware of. With this ReSharper update, the problem should be gone.
Other than a fix to the installer issues, there’s essentially nothing else in this update: if you have not installed and are not planning to install a Visual Studio 2017 Preview build, then you can safely skip this ReSharper update.
Note to ReSharper 2017.2 EAP users: the latest ReSharper Ultimate 2017.2 EAP build released last week already contains the necessary fixes.