Search icon doesn't change when Navigation Bar Default Link Hover Color is changed

Steps to reproduce:

1. Log in as Admin
2. Go to Administer wiki > Look & Feel > Themes
3. Customize the default Theme
4. Click on Navigation Bar
5. Change the Navigation Bar Default Link Hover Color

Expected results: Icon color is changed as Bell and Drawer.

Actual results: Search icon isn't changed.

Test done on IE 11.