heroku-buildpack-elixir not working with Erlang R16B

gistfile1.txt

remote: Compressing source files... done.
remote: Building source:
remote:
remote: -----> Fetching custom git buildpack... done
remote: -----> elixir app detected
remote: -----> Checking Erlang and Elixir versions
remote:        Will use the following versions:
remote:        * Stack cedar-14
remote:        * Erlang R16B
remote:        * Elixir 0.10.2
remote:        Will export the following config vars:
remote:        * Config vars DATABASE_URL
remote:        * MIX_ENV=prod
remote: -----> Stack changed, will rebuild
remote: -----> Fetching Erlang R16B
remote: -----> Installing Erlang R16B (changed)
remote:
remote: gzip: stdin: not in gzip format
remote: tar: Child returned status 1
remote: tar: Error is not recoverable: exiting now
remote: /tmp/buildpack_5232c5bed2ff9155ca4eef80bd00ff13/lib/erlang_funcs.sh: line 37: /app/tmp/cache/erlang/Install: No such file or directory
remote: -----> Fetching Elixir v0.10.2
remote: -----> Installing Elixir v0.10.2 (changed)
remote: [/app/tmp/cache/elixir-v0.10.2.zip]
remote:   End-of-central-directory signature not found.  Either this file is not
remote:   a zipfile, or it constitutes one disk of a multi-part archive.  In the
remote:   latter case the central directory and zipfile comment will be found on
remote:   the last disk(s) of this archive.
remote: unzip:  cannot find zipfile directory in one of /app/tmp/cache/elixir-v0.10.2.zip or
remote:         /app/tmp/cache/elixir-v0.10.2.zip.zip, and cannot find /app/tmp/cache/elixir-v0.10.2.zip.ZIP, period.