That is the favicon for the Google Apps Admin Console - https://admin.google.com/ . I suspect the bug only happens for Google Apps accounts (it happens on my Google Apps, not on my personal Gmail).
I thought I read that it shows up for a google app account that is also the domain administrator. But I'm not sure if this is true or not. I wouldn't say this is a "fix" as much as it's a work around for showing that other favicon.