distutils-r1.eclass: Reuse python_setup for common phases

Rewrite the python_*_all() phase running code to reuse python_setup
instead of hacking on top of python_foreach_impl. The resulting code
is a bit simpler but most importantly, it avoids duplication of code
from python-r1 and ensures that distutils-r1 common phases are directly
altered by changes in python_setup.

The code still needs to reimplement some of the internals. However, it
is mostly limited to code specific to distutils-r1, and should be more
maintainable.

eclass/distutils-r1.eclass

@@ -672,20 +672,20 @@ distutils-r1_run_phase() {
 _distutils-r1_run_common_phase() {
  local DISTUTILS_ORIG_BUILD_DIR=${BUILD_DIR}
 
- if [[ ! ${DISTUTILS_SINGLE_IMPL} ]]; then
- local best_impl patterns=( "${DISTUTILS_ALL_SUBPHASE_IMPLS[@]-*}" )
- _distutils_try_impl() {
- if _python_impl_matches "${EPYTHON}" "${patterns[@]}"; then
- best_impl=${MULTIBUILD_VARIANT}
- fi
- }
- python_foreach_impl _distutils_try_impl
- unset -f _distutils_try_impl
-
- local PYTHON_COMPAT=( "${best_impl}" )
+ if [[ ${DISTUTILS_SINGLE_IMPL} ]]; then
+ # reuse the dedicated code branch
+ _distutils-r1_run_foreach_impl "${@}"
+ else
+ local -x EPYTHON PYTHON
+ local -x PATH=${PATH} PKG_CONFIG_PATH=${PKG_CONFIG_PATH}
+ python_setup "${DISTUTILS_ALL_SUBPHASE_IMPLS[@]}"
+
+ local MULTIBUILD_VARIANTS=( "${EPYTHON/./_}" )
+ # store for restoring after distutils-r1_run_phase.
+ local _DISTUTILS_INITIAL_CWD=${PWD}
+ multibuild_foreach_variant \
+ distutils-r1_run_phase "${@}"
  fi
-
- _distutils-r1_run_foreach_impl "${@}"
 }
 
 # @FUNCTION: _distutils-r1_run_foreach_impl