NAN (Not a Number) error in color picker

Steps to reproduce:

• Bring up the color picker anywhere (a color brush, for example).

• Place your cursor at the end of the HEX value, with nothing selected (click twice, as the first click selects the hex value)

• Backspace twice

• BUG The last two digits of the value change to NAN, and you can no longer make changes in the edit box (you can reset things by moving the point in the color box). For example, if the hex value is #FFFFFF, and I want to change it to #FFFF00 - I put my cursor at the end of the hex value and backspace twice, it turns into #FFFFNAN. I can't change that any more by typing in the edit box.