I discovered this inconsistency, partly due to merge, between wporg and wpcom, and believe they should be incorporated into wporg.
In function display_element in Walk class.
i should be set to –1 in after the recursive call returns.
Consider the following example:
E1
- e2
- - e3
- - - e4
And suppose children has order: e3, e2, e4 in the children array.
First we call display_element(E1), it will traverse children array, and find e2 as E1’s child; and the resulting array becomes e3, e4.
On the next recursive call, we are trying to find the child of e2 from the remaining children array.
Yet, with i--, it will start with e4, missing e3.
So this is a tricky case that is a little hard to imagine.
However, we already saw this happening with very complicated page hierarchy in wpcom.
Therefore, we have to reset index i to –1 so that on next call, it begins with index 0.
The catch and repair bad page diff is self-explanatory.
