Transitive extra dependencies for package uninstalled when running `poetry install`

• 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: ArchLinux
• Poetry version: 1.1.4
• Link of a Gist with the contents of your pyproject.toml file:

Issue

I believe this might be related to #3224

Similar to the issue above, the problem is that if I add a package using poetry add and then run poetry install, the dependencies are getting uninstalled. Unlike #3224 though, in my case the package I am adding does not have any extras. However, the package in question is a private package (also built using poetry) which depends on another package with extras.

Steps to reproduce

Create a new project with a dependency on a package with extras

poetry new vaa-protocols
poetry add git+https://github.com/danielgtaylor/python-betterproto.git -E compiler
poetry publish -r local --build

Then create a package that depends on this package

poetry new test
poetry add vaa-protocols --source local
poetry install --no-root

Now if we run poetry install, a bunch of dependencies get uninstalled.
This happens under the following specific scenarious:

1. poetry.lock file must be present. Deleting the lock file and running install does not trigger this behavious
2. This only happens if the package vaa-protocols is installed from a custom pypi. It does not happen when using a directory or pointing to a wheel directly.
3. This only happens when I get betterproto from git. It does not happen if I get the latest package from Pypi.

Reproduce the two-project setup from the issue using pyproject.toml, poetry.lock, the custom package source, and the git dependency with the compiler extra. Start with poetry install and compare the installed dependency set before and after; done means transitive extra dependencies are retained instead of being uninstalled.