Export command requires dev source dependencies to be present

• 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).

Similar issue to: https://github.com/python-poetry/poetry/issues/875

• OS version and name: CentOS, any OS.
• Poetry version: Latest
• Link of a Gist with the contents of your pyproject.toml file: N/A

Issue

I have a dev dependency on a python package from source, e.g.

package_name = {path = "package_name"}

However, in my production build step, this package will not be present. But attempting to export when the package is not present results in the following error:

$ poetry export -f requirements.txt 

[ValueError]
Directory package_name does not exist

Dev dependencies should not be required to generate a requirements.txt for prod. I confirmed this issue is present for poetry install --no-dev as well.

Workaround

The workaround is to create a "fake" package:

mkdir package_name
touch package_name/setup.py

Reproduce the issue with a dev path dependency such as package_name = {path = "package_name"} absent, then compare poetry export -f requirements.txt with poetry install --no-dev. Start from the export command and its handling of the project dependency metadata. Done means production dependency export and installation no longer require an unavailable dev-only path package.