John Mueller from Google just announced on Google+ that they have updated the user agent for the Googlebot for smartphone.
There is a very subtle difference between the old and the new.
Here they are:
As you can see, the OS is now 8_3 vs 6_0, the AppleWebKit is now 600.1.4 instead of 536.26, the Version is 8.0 vs 6.0 and Mobile 12F70 vs 10A537e, with Safari being 600.1.4 vs 8536.25.
Google even updated their blog post from 2014 with the new details.
John from Google said, "FYI Googlebot just got a new iPhone, and is using it to check out your website."
Forum discussion at Google+.