I think it should not. Your pull request fixes a problem in that WSDL.
The WSDL is located at the URL `https://pg.eet.cz/eet/services/EETServiceSOAP/v3?wsdl`.
It references an XML Schema file at `EETXMLSchema.xsd`, which is a relative location, so it's looked for relative to the containing document, at `https://pg.eet.cz/eet/services/EETServiceSOAP/EETXMLSchema.xsd`.
The correct location is `https://pg.eet.cz/eet/services/EETServiceSOAP/v3/EETXMLSchema.xsd`, but that's not PHP's problem. You should contact the owner of the service and ask them to fix the issue. Not only PHP, but all other clients that adhere to the spec will be unable to load this file, so it's in their interest to get it resolved.
Failing that, you can
1. use an XML catalog entry on your local system to re-define where `EETXMLSchema.xsd` is located;
2. load the WSDL file from the origin URL, cache it locally, and rewrite the `schemaLocation` to contain a full relative path (`/eet/services/EETServiceSOAP/v3/EETXMLSchema.xsd`) or even an absolute URL. Then load that local WSDL.
You really want to do option 2 in production anyway, because otherwise, your SoapClient instantiation will fetch the remote WSDL file on each instantiation, which slows down your app, and may break things even if you don't make a SOAP call if the endpoint is down.
If you want to discuss this further, then the PR on GitHub is the right spot for discussing this.