Pip/conda compatibility

We discussed this one in PEP 704 - Require virtual environments by default for package installers. The greatest value is that Conda should be able to not provide the file, and allow pip to continue working normally (and the problem with the main proposal in that thread is that pip would start looking for other signals to make essentially the same decision). But Conda’s own environment (the one with Conda installed) could include the marker to discourage people from modifying it directly.