Planet: some problems with changing feed url

I decided to write a entry to my english postgres blog that streams to
planet.postgresql.org.
Since my last entry feed's url have been changed (it is still available on the
old url, but now it is a copy that may cease to exist any time.

my current RSS feed
https://nataraj.dreamwidth.org/data/rss?tag=postgres_en
is empty now. Since my last entry was more than a year ago, and blog engine
does not show it.

I think it is wise to change feed url from old to new on planet.postgresql.org
before posting new entry, in order not to get two entries in the planet feed.

But planet refuses my feed URL, saying "No entries found in blog. You cannot
submit a blog until it contains entries."
And that is actually what I really need: add a feed _before_ it has entries.

Now I think I will first create entry, and then change feed url. With luck I
would manage to do it before the old feed would be processed and do not get
double entry in planet's feed. But I still want to draw a community attention
to this problem.

I think it is better to allow to add empty feeds to planet. This will not harm
but might be helpful in some cases.

Thanks.

--
Do code for fun.