Octopus success despite of `git-write-tree` error

[EQuincerot]

When running git octopus on two branches, with some specific conditions I could not be able to describe (at least 2 branches almost identical with just the first commit changing), we get this output:

fatal: git-write-tree: error building trees
error: duplicate parent e9ca7d1ff89e6045e6a565c8be411a17725ac075 ignored
fatal: 9942d5360000000068735f5900000000b4a3f324 is not a valid object
usage: git update-ref [options] -d <refname> [<oldval>]
   or: git update-ref [options]    <refname> <newval> [<oldval>]
   or: git update-ref [options] --stdin [-z]

    -m <reason>           reason of the update
    -d                    delete the reference
    --no-deref            update <refname> not the one it points to
    -z                    stdin has NUL-terminated arguments
    --stdin               read updates from stdin

-----------------------------------------------------------
OCTOPUS SUCCESS

The result of the octopus is pretty weird: it contains only one of the conflicting branches.
Using octopus 1.4.

I would expect an error from the octopus. It seems this bug is not reproducible in every environment. Hard to guess why.

[apflieger]

Was the index in a conflict state before executing git octopus?

[danoliv]

We had the same problem with the version 1.4, it looks fixed in the version 2.0.