Poetry doesn't find package in devpi repository

• 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: Ubuntu 19.10
• Poetry version: 1.0.0b3

Issue

I have a private repository https://pypi.g.mycompany/:

devpi-server-5.1.0
devpi-web-3.5.2

and I want to install package foo from it, poetry doesn’t find it:

[SolverProblemError]
Because project depends on foo (0.19.0) which doesn't match any versions, version solving failed.

Traceback (most recent call last):
Traceback (most recent call last):
  File "/home/yan/.poetry/bin/poetry", line 14, in <module>
    main()
  File "/home/yan/.poetry/lib/poetry/console/__init__.py", line 5, in main
    return Application().run()
  File "/home/yan/.poetry/lib/poetry/_vendor/py2.7/clikit/console_application.py", line 139, in run
    trace.render(io, simple=isinstance(e, CliKitException))
  File "/home/yan/.poetry/lib/poetry/_vendor/py2.7/clikit/ui/components/exception_trace.py", line 57, in render
    self._render_traceback(io, tb)
  File "/home/yan/.poetry/lib/poetry/_vendor/py2.7/clikit/ui/components/exception_trace.py", line 67, in _render_traceback
    io.write_line("".join(traceback.format_list(frames)))
  File "/usr/lib/python2.7/traceback.py", line 39, in format_list
    item = '  File "%s", line %d, in %s\n' % (filename,lineno,name)

pyproject.toml:

[tool.poetry]
name = "projects"
version = "0.1.0"
description = ""
authors = []

[tool.poetry.dependencies]
python = "^3.7"
foo = {version = "0.19.0", source = "xxx"}

[tool.poetry.dev-dependencies]
pylint = "^2.4"

[[tool.poetry.source]]
name = "xxx"
url = "https://pypi.g.mycompany/root/pypi/+simple"

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

[Yanpas]

Adding default = true to tool.poetry.source did help

[neersighted]

Closing as this is a configuration issue, and we already have asks in for better docs around source resolution order.