pkgctl: git_diff_tree command not found

I am getting a git_diff_tree: command not found error, but the detected pkgrel is fine.

$ pkgctl build --rebuild --release --testing --db-update
==> Updating pacman database cache
:: Synchronizing package databases...
 core downloading...
 extra downloading...
 community downloading...
 multilib downloading...
==> Building gopass
  -> repo: extra-testing
  -> arch: x86_64
/usr/local/share/devtools-git-poc//lib/build/build.sh: line 311: git_diff_tree: command not found
==> Bumping pkgrel to 4

The code in question is https://gitlab.archlinux.org/archlinux/devtools/-/blob/git-packages/src/lib/build/build.sh#L311 and I guess it could just miss to include https://gitlab.archlinux.org/archlinux/devtools/-/blob/git-packages/src/lib/util/git.sh#L11-24