Extended ASCII characters in page titles break link rendering under IE8

Steps to reproduce

1. Using Confluence 5.3-OD-15, create a child page of a space homepage that has an extended ASCII character in the title (ø, å, ü, etc.):
   
2. Using IE8, mouse-over the link of the parent page in the sidebar that's under the "Child Pages" heading in the sidebar.

The URL that the parent page is linked to is https://example.atlassian.net/wiki/pages/viewpage.action?src=contextnavchildmode. Note the total lack of any actual page ID.

This also affects almost any generated link on the page. The problem seems to be coming from the com.atlassian.confluence.plugins.confluence-space-ia:soy-resources.js script.