Attaching to running debug server fails because Qt Creator ignores designated port and tries using tcp::0

Debug -> Start -> Attach to Running Debug Server

When I try to attach to a remote GDB target via Debug -> Start Debugging -> Attach to Running Debug Server..., no matter what port I use the actual gdb command is `target remote tcp::0`.

Qt Creator then fails with "Connecting to remote server failed: tcp::0. Can't assign request address".

Rolling back to Qt Creator 3.6.x resolves the problem and the debug log shows the expected `target remote tcp::3333`.