vcpkg: make builtin-baseline work

Consider this vcpkg.json file:

  {
    "dependencies": [ "fmt", "zlib" ],
    "builtin-baseline": "101ae1f63a22d262f80a68034a1550da5dfdd05f"
  }

Before this change, if you tried to run “vcpkg install” with that
vcpkg.json file, then vcpkg would fail with this error:

  error: while checking out baseline from commit '101ae1f63a22d262f80a68034a1550da5dfdd05f', failed to `git show` versions/baseline.json. This may be fixed by fetching commits with `git fetch`.
  error: git failed with exit code: (128).
  fatal: not a git repository: '.git'
  while checking out baseline 101ae1f63a22d262f80a68034a1550da5dfdd05f

This commit fixes that problem.

pkgs/by-name/vc/vcpkg/package.nix

@@ -1,6 +1,7 @@
 { fetchFromGitHub
 , stdenvNoCC
 , lib
+, git
 , vcpkg-tool
 , makeWrapper
 , doWrap ? true
@@ -14,7 +15,11 @@ stdenvNoCC.mkDerivation (finalAttrs: {
     owner = "microsoft";
     repo = "vcpkg";
     rev = finalAttrs.version;
-    hash = "sha256-eDpMGDtC44eh0elLWV0r1H/WbpVdZ5qMedKh7Ct50Cs=";
+    hash = "sha256-omHlViym0hs02cn/25nUVtNVa38yowByttZ2vjqpWhs=";
+    # If you use a builtin-baseline in a vcpkg.json file, then vcpkg will try
+    # to run “git show <baseline-commit>”. We need a deep clone in order to
+    # ensure that that works.
+    deepClone = true;
   };
 
   nativeBuildInputs = [ makeWrapper ];
@@ -32,12 +37,21 @@ stdenvNoCC.mkDerivation (finalAttrs: {
   installPhase = ''
       runHook preInstall
 
-      mkdir -p "$out/bin" "$out/share/vcpkg/scripts/buildsystems"
-      cp --preserve=mode -r ./{docs,ports,triplets,scripts,.vcpkg-root,versions,LICENSE.txt} "$out/share/vcpkg/"
+      mkdir -p "$out/bin" "$out/libexec/vcpkg" "$out/share/vcpkg/scripts/buildsystems"
+      cp --preserve=mode -r ./{.git,docs,ports,triplets,scripts,.vcpkg-root,versions,LICENSE.txt} "$out/share/vcpkg/"
 
       ${lib.optionalString doWrap ''
+        # If you use a builtin-baseline in a vcpkg.json file, then vcpkg will
+        # try to run “git show” on $out/share/vcpkg. By default, Git will fail
+        # if a Git repo isn’t owned by the current user. We create a wrapper
+        # for git here to make sure that the “git show” command succeeds, even
+        # if the user running vcpkg doesn’t own $out/share/vcpkg.
+        makeWrapper "${git}/bin/git" "$out/libexec/vcpkg/git" \
+          --add-flags -c --add-flags safe.directory="$out/share/vcpkg"
+
         makeWrapper "${vcpkg-tool}/bin/vcpkg" "$out/bin/vcpkg" \
-          --set-default VCPKG_ROOT "$out/share/vcpkg"
+          --set-default VCPKG_ROOT "$out/share/vcpkg" \
+          --prefix PATH : "$out/libexec/git"
       ''}
 
       ln -s "$out/bin/vcpkg" "$out/share/vcpkg/vcpkg"