freebsd-amd64-head (FreeBSD/amd64 HEAD (Gabor Pali)), build 839, Failure

[Builder]

freebsd-amd64-head (FreeBSD/amd64 HEAD (Gabor Pali)), build 839

Build failed
Details: http://haskell.inf.elte.hu/builders/freebsd-amd64-head/839.html

git clone                    | Success
git clone (Windows tarballs) | Success
create mk/build.mk           | Success
repo versions                | Failure: Just (ExitFailure 1)

Build failed
Details: http://haskell.inf.elte.hu/builders/freebsd-amd64-head/839.html

-------------- next part --------------
Entering '.arc-linters/arcanist-external-json-linter'
85ece0f8653e7b1e7de6024d372cfeaf36ab5fa9 Don't construct intermediate dictionary
Entering 'libffi-tarballs'
fatal: ambiguous argument 'HEAD^..': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
Stopping at 'libffi-tarballs'; script returned non-zero status.