[Pytest-commit] Issue #526: "ValueError: Plugin already registered" with symlinked copy (via `virtualenv .`) (hpk42/pytest)

[Daniel Hahler]

New issue 526: "ValueError: Plugin already registered" with symlinked copy (via `virtualenv .`)
https://bitbucket.org/hpk42/pytest/issue/526/valueerror-plugin-already-registered-with

Daniel Hahler:

I have been running into an issue where virtualenv's `fix_local_scheme` (https://github.com/pypa/virtualenv/blob/develop/virtualenv.py#L1532-1550) creates a `local` folder full of symlinks to all files in the current directory for `virtualenv .`.
(`virtualenv .` is used by pytest_django, and I have seen it being used elsewhere already).

While this is more a problem with virtualenv (reported at https://github.com/pypa/virtualenv/issues/617) and pytest_django (reported at https://github.com/pelme/pytest_django/issues/102), it would be nice if pytest could be more forgiving and only emit a warning, potentially pointing out that it is the same (symlinked) file?

(`fix_local_scheme` only applies to a Python installation with `sysconfig._get_default_scheme() == 'posix_local'`, which is the case for Ubuntu.
The default scheme for a custom installation of 3.4.0 is 'posix_prefix')