[Nix-dev] Use shallow copying in fetchgit

[Peter Simons]

Does anyone see a problem with applying this patch?

diff --git a/pkgs/build-support/fetchgit/builder.sh b/pkgs/build-support/fetchgit/builder.sh
index ed3af4a..2b7e761 100644
--- a/pkgs/build-support/fetchgit/builder.sh
+++ b/pkgs/build-support/fetchgit/builder.sh
@@ -9,7 +9,7 @@ header "exporting $url (rev $rev) into $out"
 git init $out
 cd $out
 git remote add origin "$url"
-git fetch --progress origin
+git fetch --depth 1 --progress origin
 git remote set-head origin -a || (
     test -n "$rev" && echo "that's ok, we want $rev" || exit 1)