On Linux, NuGet.config and NuGet.Config are different files. Both can exist in the same folder, and attempts to read the "wrong" file will result in a file not found error. As a result, we have a patch in the NuGet repo, eng/source-build-patches/0001-Rename-NuGet.Config-to-NuGet.config-to-account-for-a.patch authored by @crummel, to reconcile a bad casing assumption. However, on Windows and Mac, this patch fails to apply with git apply as those two filenames are considered equivalent. This breaks the build on non-Linux.
We either need a way to separate out source build patches by OS applicability (e.g. eng/source-build-patches/$(TargetOS)/), or need to eliminate the patch.