chore: enable pipstar by default

The most recent improvements to the platform definitions allow us to
enable pipstar by default, which means that we can get rid of the
interpreter usage in the extension evaluation phase.

Fixes #2949

Author: aignas

CHANGELOG.md

@@ -78,6 +78,10 @@ END_UNRELEASED_TEMPLATE
   platform, consider helping set us up CI for them and update the documentation.
 * (ci) We are now testing on Ubuntu 22.04 for RBE and non-RBE configurations.
 * (core) #!/usr/bin/env bash is now used as a shebang in the stage1 bootstrap template.
+* (pypi) From now on `pipstar` is enabled by default for all builds. To disable it, consider
+  setting env variable `RULES_PYTHON_ENABLE_PIPSTAR` to `0`. If there are reasons why you have to
+  keep it disabled, it is a bug and we would like to hear about it, please create a ticket in our
+  github issue tracker.
 
 {#v0-0-0-fixed}
 ### Fixed

python/private/internal_config_repo.bzl

@@ -21,7 +21,7 @@ settings for rules to later use.
 load(":repo_utils.bzl", "repo_utils")
 
 _ENABLE_PIPSTAR_ENVVAR_NAME = "RULES_PYTHON_ENABLE_PIPSTAR"
-_ENABLE_PIPSTAR_DEFAULT = "0"
+_ENABLE_PIPSTAR_DEFAULT = "1"
 _ENABLE_PYSTAR_ENVVAR_NAME = "RULES_PYTHON_ENABLE_PYSTAR"
 _ENABLE_PYSTAR_DEFAULT = "1"
 _ENABLE_DEPRECATION_WARNINGS_ENVVAR_NAME = "RULES_PYTHON_DEPRECATION_WARNINGS"