fix(tvix): apply cbtemulator patch in tvix view

This tells josh to include the patch from
third_party/overlays/patches/cbtemulator-uds.patch at
nixpkgs/cbtemulator-uds.patch.

We then use the `additionalOverlays` feature introduced earlier, and
pass it an overlay adding the patch to `cbtemulator`.

This only gets applied if tvix/shell.nix is not called with a pkgs
argument, which is the case in the tvix view.

Change-Id: I7bc5543460ddd30325ab0998e891c15fcaf8bcfe
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11408
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: flokli <flokli@flokli.de>

tvix/shell.nix

@@ -8,7 +8,16 @@
   pkgs ? (import ./nixpkgs {
     depotOverlays = false;
     depot.third_party.sources = import ./sources { };
-    additionalOverlays = [ ];
+    additionalOverlays = [
+      (self: super: {
+        # https://github.com/googleapis/google-cloud-go/pull/9665
+        cbtemulator = super.cbtemulator.overrideAttrs (old: {
+          patches = old.patches or [ ] ++ [
+            ./nixpkgs/cbtemulator-uds.patch
+          ];
+        });
+      })
+    ];
   })
 , ...
 }:

views/tvix/workspace.josh

@@ -1,8 +1,9 @@
 :/third_party:[
-    ::nixpkgs/
+    ::nixpkgs/,
     ::sources/
 ]
 ::tvix:exclude[
     ::tvix/default.nix
     ::tvix/**/default.nix:exclude[::tvix/eval/src/tests/tvix_tests/directory/default.nix]
 ]:/tvix
+::third_party/overlays/patches/cbtemulator-uds.patch:/third_party/overlays/patches:prefix=nixpkgs