Only use hashes in requirements.txt if there are no VCS repositories

• 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). (n/a)

• OS version and name: macOS 10.5.5 Beta

• Poetry version: 1.0.5

• Contents of pyproject.toml file:

[tool.poetry]
name = "test-poetry-proj"
version = "0.1.0"
description = "desc"
authors = ["Sumanth Ratna <sumanthratna@gmail.com>"]

[tool.poetry.dependencies]
python = "^3.6.1"
numpy = "^1.18.4"
hyperopt = {git = "https://github.com/hyperopt/hyperopt.git"}


[tool.poetry.dev-dependencies]
pytest = "^5.4.2"

[tool.poetry.scripts]

[build-system]
requires = ["poetry>=0.12"]
build-backend = "poetry.masonry.api"

Issue

When I run poetry export -f requirements.txt > requirements.txt, the resulting requirements.txt file has a bunch of hashes. Unfortunately, that means I can't run pip install -r requirements.txt on another machine, because it returns this error:

ERROR: Can't verify hashes for these requirements because we don't have a way to hash version control repositories:
    hyperopt from git+https://github.com/hyperopt/hyperopt.git#egg=hyperopt (from -r requirements.txt (line 192))

I'm labeling this as a bug report instead of a feature request because this seems like a fault in the way Poetry behaves when exporting.

Reproduce the issue with the provided pyproject.toml and poetry export -f requirements.txt, then inspect the export path that handles VCS repositories and requirement hashes. Verify the result by running pip install -r requirements.txt with the generated file and confirm that the VCS dependency no longer causes hash verification to fail.