Description of problem:
If you add a custom login background image, and later change it, you have to save it at least twice.


How reproducible:
100%

Steps to Reproduce:
1.add an image to Custom Login Background Image and upload it.
2.Select "Use Custom Login Background Image"
3.save
4.Choose a new file and Upload it to Custom Login Background Image


Actual results:
there is no option to save. the button is greyed out.

Expected results:
After changing one's settings, one should have the option to save said settings.

Additional info:
Workaround:
Either de-select "Use Custom Login Background Image" and save before adding the new image, or deselect "Use Custom Login Background Image", save, click "Use Custom Login Background Image", and save again. Either way you need to save twice. Sometimes you have to save up to 4 times, and sometimes even after the image is applied and working, the "Use Custom Login Background Image" mysteriously becomes unchecked, even though science tells us it's actually being used.