Reset to default doesn't work when there is an error with user input

Assume there is a module with a system_settings_form with custom validation (example: a form that allows the user to enter a number for something, the number is entered into a textbox and the form validation function uses is_numeric()).

Now say the user puts 'd' into the box and saves the settings. As we would expect, there is an error message displayed (according to what was defined in the form validation function). But now, with the current page (with the error on it, and the value 'd' still in the box) if the user presses "Reset to defaults" it won't do anything. I have found that the button will not do anything until the user corrects their error.

This is for most cases, minor, but could easily become major say if there was a user who didn't know about this and was trying to fix their mistake by pressing the reset button.