During the mad rush for all SEOs to migrate from HTTP to HTTPS to get that tiny little boost in their rankings with the new Google HTTPS Algorithm, many noticed a failure within the Google Webmaster Tools Change of Address Tool.
In short, when you do a URL change in Google, from one URL to another, i.e. HTTP to HTTPS, you want to use the Change Of Address Tool, as the Google documents clearly say. But it simply does not work from HTTP to HTTPS within Google Webmaster Tools.
Here is a screen shot (click to enlarge) of me trying to change it for HTTP rustybrick.com to HTTPS rustybrick.com:
The option is not there. Google is indeed aware of it, John Mueller of Google said so on Google+. In response to a question on why it is not working, John wrote, "unfortunately that's still in work :-/. In the meantime, I'd just use normal 301s."
So I guess go 301 and forget about the change of address tool, hopefully it won't be an issue?