I think that will be fixed once we update our Travis Builds to use Ubuntu 16.04 LTS. Right now our builds are using Ubuntu 14.04 LTS. I'm going to try to update them on my fork this week. If they pass, I'll push the new files to master which will update the glibc to 2.23 from what I can tell. Sadly I think we're going to stick to LTS for now.
In other news, I did update the appimage scripts to correctly name the files so we know which commit they come from. Here's the newest build for example.
Long name, but at least if someone opens a bug report, all the version info we need is in the filename.