Запятая не нужна:
> не помню почему.
http://www.evartist.narod.ru/text1/49.htm
§107. Запятая между главным и придаточным предложениями
Примечание 2. Не ставится запятая между главным и следующим за ним придаточным предложением:
в) если придаточное предложение состоит из одного только союзного слова (относительного местоимения или наречия)

Only to make sure I understood:
The reason for not putting a comma here is that the subordinate clause consists of only one word?

I have a question here, not related to the comma:
As it's "всё равно", should we add another sentence (yet another variant), with "всё равно" instead of "все равно", to make it easier for beginners in Russian?

> The reason for not putting a comma here is that the subordinate clause consists of only one word?
Exactly.

Since "все равно" doesn't exist I don't think it's necessary. However, I personnaly always write "ё".

Thanks.
It's interesting: you always write "ё", in all its occurrences? I thought that Russians don't always write it. ☺
Maybe you are an exception. ☺

I mean here in Tatoeba.

Oh, I see.
Then, please ignore my comment above. :)

Well, I don't mind being an exception. :)

No response for more than 2 weeks.
Corrected.