Sorry, I only know how to apply git c source code patches onto a git
repository, not a Linux OS.
What I was expecting needing to do is to checkout nouveau's fixed code, build
it and somehow install it over the version in the package manager/this
distribution, at which point I would hopefully have a working driver.

In my first post I of course meant "jessie", not "stretch" (testing).

I succeeded at building nvagetbios and nvbios, but both fail:

anonymissimus@debian:/media/HD3_SOURCE/envytools/nva$ ./nvagetbios
WARN: Can't probe 0000:01:00.0
PCI init failure!

anonymissimus@debian:/media/HD3_SOURCE/envytools/nvbios$ ./nvbios mybios.rom
warning: No strap specified
fopen: No such file or directory
Failed to read VBIOS!