When I go to edit a User, the email field pre-populates with my site email, rather than the actual User's email.
I tried it in Safari, Chrome and Firefox (Mac). On Firefox it won't even let me enter a new email address. As soon as I leave the field it reverts to the site email.
Is that a bug?
I had a similar problem today but all of the relevant field were autopopulating. In my case it is because my password saver program was recognizing the fields and completing them for me. It could be that you have selected to have your browser autopopulate fields for you. I confirmed it by signing out of my password program.
I hope this gives you some ideas.
Yes - if you are using a password manager and it is set to auto-complete or auto-fill form fields you may find your email is always dropped into an email form field. This can be fairly frustrating so do suggest turning it off if you are able to in your settings.