mix deps.get error on new server

gistfile1.txt

deployer@staging-rmv1:~/app/rmv$ mix deps.get
** (UndefinedFunctionError) undefined function Hex.shell/0
    (hex) Hex.shell()
    (hex) lib/hex/remote_converger.ex:91: anonymous fn/2 in Hex.RemoteConverger.check_deps/1
    (elixir) lib/enum.ex:604: Enum."-each/2-lists^foreach/1-0-"/2
    (elixir) lib/enum.ex:604: Enum.each/2
    (hex) lib/hex/remote_converger.ex:27: Hex.RemoteConverger.converge/2
    (mix) lib/mix/dep/converger.ex:85: Mix.Dep.Converger.all/4
    (mix) lib/mix/dep/converger.ex:47: Mix.Dep.Converger.converge/4
    (mix) lib/mix/dep/fetcher.ex:16: Mix.Dep.Fetcher.all/3