Merge master into staging

pkgs/os-specific/linux/zfs/default.nix

@@ -28,7 +28,7 @@ let
         versionAtLeast kernel.version incompatibleKernelVersion then
        throw ''
          Linux v${kernel.version} is not yet supported by zfsonlinux v${version}.
-         ${stdenv.lib.optional (!isUnstable) "Try zfsUnstable or set the NixOS option boot.zfs.enableUnstable."}
+         ${stdenv.lib.optionalString (!isUnstable) "Try zfsUnstable or set the NixOS option boot.zfs.enableUnstable."}
        ''
     else stdenv.mkDerivation rec {
       name = "zfs-${configFile}-${version}${optionalString buildKernel "-${kernel.version}"}";
@@ -168,7 +168,7 @@ in {
 
   zfsUnstable = common rec {
     # comment/uncomment if breaking kernel versions are known
-    incompatibleKernelVersion = null;
+    incompatibleKernelVersion = "4.16";
 
     # this package should point to a version / git revision compatible with the latest kernel release
     version = "2018-04-04";