As I mentioned in my previous blog post, when we do L10n repackages it happens by unpackaging an en-US build and overwriting the en-US dtd and property files with the ones of that locale.
Part of this process requires checking out part of the en-US code and the current problem is that we do NOT checkout the same Source Stamp than what was used to generate the en-US build, since we do not really have a way to know what was the Source Stamp used.
There is a bug which I started to work on last week and the patches would allow us to have the Source Stamp in application.ini if a MOZ_CO_DATE variable is set when checking out the source code. Therefore, if we have this working we will have it easy to know what Source Stamp was used for an en-US build and we will be able to check out exactly the same Source Stamp when doing L10n repackages and we should not be unsynchronized at all.
NOTE: The previous patches mentioned do not change anything at all if no MOZ_CO_DATE is set.