lerna: import failure: "git diff header lacks filename information when removing 1 leading pathname component"

I’m trying to init a new lerna instance, and import some (very large) old repo’s. And I am running into this error.

lerna import ../<some-large-repo>/
Lerna v2.0.0-beta.30
About to import 1947 commits into from ../<some-large-repo>/ into packages/<some-large-repo>
? Are you sure you want to import these commits onto the current branch? Yes
Errored while running ImportCommand.execute
Failed to apply commit a76cb3c23.
Error: Command failed: git am -3
error: git diff header lacks filename information when removing 1 leading pathname component (line 15046)
error: could not build fake ancestor

Rolling back to previous HEAD (commit 3ff03a0).