Michael K. Edwards wrote:
But note that in principle the creation of derivative works can be infringement even if they are not distributed, and I haven't dug through case law to see exactly how far 17 USC 117 can be stretched from run-time use to local builds.
Thankfully, you need not do so; GPL (2) give permission to make derivative works. As long as you don't distribute or publish the work (which is the case here), you need only (1) make notes on files you modified; (2) the thing with spewing the GPL notice for interactive programs.