The source code for a work means the preferred form of the work for
making modifications to it.
Whether combining lots of patches into one large patch constitutes a change in "form" would be an argument for the lawyers if this ever goes to court, which I very much doubt.
In my opinion, however, the case is pretty clear -- you simply do not modify that large a patch file. Therefore it's not a "preferred form". Therefore Red Hat is, ideally if not materially, in breach of the GPL.
Disclaimer: I am not a lawyer, not do I play one on TV.