bug#29655: Elixir build has an undeterministic build error

[Pjotr Prins]

The epipe error suggests a new external process is invoked (git)
which does not terminate properly and does not close the pipe. Maybe
it tries to access the network layer. The calling program throws an
epipe error. I see something similar happening
here: https://gist.github.com/knewter/533d22eb69ef1036c22a