Something is maybe hardcoded or badcoded, that forces
phpMyAdmin to look
for /themes/darkblue_orange/img/error.ico, and that
results in a 404 not found when phpMyAdmin is not
installed in the root path of the given url (p.e.
inside the folder phpmyadmin -
I personally fixed the problem with an alias in Apache
(to avoid such 404 in my logs), but this is a bug.