Hi,
This is related to [0]. According to [1] we should replace the PmaAbsoluteUri directive with PmaUri, which would accept relative URLs. Or maybe we don't need this directive anymore.
See mainly checkPmaAbsoluteUri().
It's a little late for 4.5.0 and even for 4.5.x, so I suggest we target 4.6 for this.
[0] https://github.com/phpmyadmin/phpmyadmin/issues/11412 [1] https://en.wikipedia.org/wiki/HTTP_location