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.