fetchgit: add lfs support

pkgs/build-support/fetchgit/builder.sh

···
 
 $SHELL $fetcher --builder --url "$url" --out "$out" --rev "$rev" \
   ${leaveDotGit:+--leave-dotGit} \
+  ${fetchLFS:+--fetch-lfs} \
   ${deepClone:+--deepClone} \
   ${fetchSubmodules:+--fetch-submodules} \
   ${branchName:+--branch-name "$branchName"}

pkgs/build-support/fetchgit/default.nix

···
-{stdenvNoCC, git, cacert}: let
+{stdenvNoCC, git, git-lfs, cacert}: let
   urlToName = url: rev: let
     inherit (stdenvNoCC.lib) removeSuffix splitString last;
     base = last (splitString ":" (baseNameOf (removeSuffix "/" url)));
···
   # successfully. This can do things like check or transform the file.
   postFetch ? ""
 , preferLocalBuild ? true
+, fetchLFS ? false
 }:
 
 /* NOTE:
···
   inherit name;
   builder = ./builder.sh;
   fetcher = ./nix-prefetch-git;  # This must be a string to ensure it's called with bash.
-  nativeBuildInputs = [git];
+
+  nativeBuildInputs = [ git ]
+    ++ stdenvNoCC.lib.optionals fetchLFS [ git-lfs ];
 
   outputHashAlgo = "sha256";
   outputHashMode = "recursive";
   outputHash = sha256;
 
-  inherit url rev leaveDotGit fetchSubmodules deepClone branchName postFetch;
+  inherit url rev leaveDotGit fetchLFS fetchSubmodules deepClone branchName postFetch;
 
   GIT_SSL_CAINFO = "${cacert}/etc/ssl/certs/ca-bundle.crt";
 

pkgs/build-support/fetchgit/nix-prefetch-git

···
 deepClone=$NIX_PREFETCH_GIT_DEEP_CLONE
 leaveDotGit=$NIX_PREFETCH_GIT_LEAVE_DOT_GIT
 fetchSubmodules=
+fetchLFS=
 builder=
 branchName=$NIX_PREFETCH_GIT_BRANCH_NAME
 
···
             --quiet) QUIET=true;;
             --no-deepClone) deepClone=;;
             --leave-dotGit) leaveDotGit=true;;
+            --fetch-lfs) fetchLFS=true;;
             --fetch-submodules) fetchSubmodules=true;;
             --builder) builder=true;;
             -h|--help) usage; exit;;
···
     local dir="$1"
     local url="$2"
     local rev="${3:-HEAD}"
+
+    if [ -n "$fetchLFS" ]; then
+        HOME=$TMPDIR
+        git lfs install
+    fi
 
     # Perform the checkout.
     case "$rev" in