Leland Chee (Keeper of the Holocron, and thus pretty much the main authority on canon) confirmed that this did indeed happen.
(explaining how canon database works) ... Source A contradicts Source B. More likely than not, if Source A is from the films and Source B is from the EU, we'll use Source A. Of course, there can always be exceptions which is why the case-by-case determination is always in effect no matter what the Sources." (src)
When pressed for details on the same thread, he indicated this (Tasty Taste is his ID on that starwars.com forum):
From: Tasty Taste
Date Posted: Nov 07, 2005 10:06 AM
> I'd be interested to know what circumstances would allow the EU to overthrow the films...
Well, you've got the Boba Fett thing. Then there's stormtroopers where there's a bunch of sources released prior to Ep2 that said that they were human recruits. Hence we established that while most stormtroopers are clones, there are some that are recruits.