A key element of BGP loop prevention is not doing this.
I am fully awared of it.
Wanting to do this suggests to me your BGP design is wrong or you are using the wrong solution for the job.
Complete guess: are you trying to survive when your AS becomes partitioned? If so, the easy way (given you say "provider") is simply to carry around an IGP or BGP default route pointing at said provider.
Indeed, I want to survive AS split. And I must say that this default route is very simple solution and i will gonna use it. However, accepting own AS in AS-PATH could be handy too. Cisco can do it, Quagga can do it too, it would be good to have it in bird. Of course, it must be turned off by default and you have to know what are you doing when enabling it. When everything is all right, you have to take care that your internal path is always choosen. When AS is splitted, it will simply route through internet, just like your 'default route' does. Default route might not be such effective when you have more then one upstream provider, since you have to choose default route throu one of them, and if you have bad luck and both internal connection and this particular provider will fail at the same time, you're toasted. Regards -- Adrian Czapek