/bin/sh: poetry: not found

• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: Docker python:3.6.5-alpine3 via macOS 10.14
• Poetry version: master
• Link of a Gist with the contents of your pyproject.toml file:

Issue

Hi there,

Today a Docker container which houses an NLP training platform broke. It seems the issue is that Poetry isn’t being installed properly into the container during the container build phase. I don’t see any problems until I try to use the Poetry executable.

Here’s some output from the Docker build:

Retrieving Poetry metadata
# Welcome to Poetry!
This will download and install the latest version of Poetry,
a dependency and package manager for Python.
It will add the `poetry` command to Poetry's bin directory, located at:
$HOME/.poetry/bin
This path will then be added to your `PATH` environment variable by
modifying the profile file located at:
$HOME/.profile
You can uninstall at any time with `poetry self:uninstall`,
or by executing this script with the --uninstall option,
and these changes will be reverted.
Installing version: 0.12.2
  - Downloading poetry-0.12.2-linux.tar.gz (8.53MB)
Poetry (0.12.2) is installed now. Great!
To get started you need Poetry's bin directory ($HOME/.poetry/bin) in your `PATH`
environment variable. Next time you log in this will be done
automatically.
To configure your current shell run `source $HOME/.poetry/env`

...

Step 8/15 : WORKDIR /app
 ---> Running in b3131b487bb2
Removing intermediate container b3131b487bb2
 ---> 8bab84b160e7
Step 9/15 : COPY pyproject.lock pyproject.toml /app/
 ---> f9a9ecb5af2d
Step 10/15 : RUN poetry update && poetry install
 ---> Running in 02c7de951592
/bin/sh: poetry: not found
The command '/bin/sh -c poetry update && poetry install' returned a non-zero code: 127

As recently as a few days ago this container built without any issue.