[Avodah] Burning sold chameitz

[Ben Waxman via Avodah]

http://bit.ly/2pui5Hy

A rav gave over some quick halachot and cited the Shulhan Aruch that if 
one finds chameitz in one's home, you cover it (if you find it on 
shabbat/yom tov) and later burn it, or burn it right away (cholo moed).

I asked, if one sold one's chameitz, how can you burn it? It now belongs 
to the non-jew. This rav (and second rav) said that the sale only 
includes the chameitz that you specify. If you don't have a piece of 
chameitz in mind, you didn't sell it.

OK. But today i looked at the contract used to authorize the rabbinate 
to sell one's chameitz (linked above). It says very clearly, that they 
are selling ALL of a person's chameitz, everything in all of his 
properties. It makes no mention of what you have in mind. If a contract 
say "ALL" it means all, n'est pas?

So my question returns: would someone burn chameitz that they found?

Ben