How should I enter values on a budget in gnucash ?

[Geert Janssens]

Background of my question: recently someone proposed a fix for the gnucash 
budget balance sheet report [1] because it was showing incorrect values 
(according to the poster).

As budgetting is an area of gnucash I'm not at all familiar with all, I'm 
having trouble estimating whether the patch submitter really did discover a 
bug and the fix is valid, or whether he is using the budget feature 
incorrectly.

My question is simply this:
I want to budget a repayment of a credit card (from my bank account).

How should I enter this in a budget:
Bank: 100.00-
Credit card: 100.00-

Or
Bank: 100.00-
Credit card: 100.00(+)

I would expect the latter as I think transactions need to balance. However the 
other person expects the former.

I've read the gnucash documentation which is unfortunately not showing any 
example or detail in this regard.

In addition there's an outstanding bug report [2] with the exact same request, 
so answering this here, would solve two problems at once :)

Thanks,

Geert


[1] https://github.com/Gnucash/gnucash/pull/120
[2] https://bugzilla.gnome.org/show_bug.cgi?id=689754