Yes, all patch files in the repo have a `.patch` extension, and future patches should have too.

But, the reason this guard is required is because non-patch files can be copied into a certain location in the build directory via the `patches` easyconfig parameter. See https://github.com/hpcugent/easybuild-easyconfigs/blob/master/easybuild/easyconfigs/o/OpenBLAS/OpenBLAS-0.2.6-gompi-1.4.10-LAPACK-3.4.2.eb for example, where `large.tgz` and `timing.tgz` are handled that way.