[Alloy MVC] Search box does not work for unmapped domain when a mapped domain exist

Steps to reproduce

Steps to reproduce

1. Set up a CMS site with one primary host for english culture, one primary host for non- specific culture, for example
2. 
3. Browse the site using no specific culture host (http://vnlabvm50.ep.cms:17003/)
   
4. Enter some keywords (e.g "Alloy) into search box, hit Enter
   

Expected: Site returns search list on the same host (no redirect)

Actual:
1. For Alloy template site, it returns correct search result list but auto navigate to English culture host. that is http://vnlabvm50:17003/search/?q=alloy
2. For AlloyMVC template site, it keeps the host name, but got 404 not found error



Note: No such issue if I remove the host with english culture.

Developers Note:

It seems like we have introduced a harder stance on routing to an unbound site and will not route if there are language mappings. Most other links on the site will be generated to the mapped domain (this is true for previous versions as well) and so will the WebForms site, but on the MVC site, the search form action only uses the virtual path to the search page, which causes the 404.