math/sage: chase the upgrade to py38-setuptools to 57.0.0

The latest upgrade of py38-setuptools to 57.0.0 introduced a conflict
with some files installed by SageMath: remove them.

math/sage/Makefile

@@ -2,7 +2,7 @@
 
 PORTNAME=	sage
 PORTVERSION=	9.2
-PORTREVISION=	14
+PORTREVISION=	15
 CATEGORIES=	math
 MASTER_SITES=	https://mirrors.xmission.com/sage/src/		\
 		http://mirrors.xmission.com/sage/src/		\
@@ -568,8 +568,10 @@ do-install:
 
 post-install:
 	${RM} ${STAGEDIR}${PREFIX}/lib64 ${STAGEDIR}${PREFIX}/libdata/pkgconfig/blas.pc	\
+		${STAGEDIR}${PYTHONPREFIX_SITELIBDIR}/distutils-precedence.pth	\
 		${STAGEDIR}${PREFIX}/libdata/pkgconfig/cblas.pc	\
 		${STAGEDIR}${PREFIX}/libdata/pkgconfig/gsl.pc	\
 		${STAGEDIR}${PREFIX}/libdata/pkgconfig/lapack.pc
+	${RM} -r ${STAGEDIR}${PYTHONPREFIX_SITELIBDIR}/_distutils_hack
 
 .include <bsd.port.post.mk>

math/sage/pkg-plist

@@ -49,11 +49,6 @@ include/ratpoints.h
 lib/libratpoints.a
 %%PYTHON_SITELIBDIR%%/__pycache__/sage_conf.cpython-%%PYTHON_SUFFIX%%.pyc
 %%PYTHON_SITELIBDIR%%/__pycache__/sagetex.cpython-%%PYTHON_SUFFIX%%.pyc
-%%PYTHON_SITELIBDIR%%/_distutils_hack/__init__.py
-%%PYTHON_SITELIBDIR%%/_distutils_hack/__pycache__/__init__.cpython-%%PYTHON_SUFFIX%%.pyc
-%%PYTHON_SITELIBDIR%%/_distutils_hack/__pycache__/override.cpython-%%PYTHON_SUFFIX%%.pyc
-%%PYTHON_SITELIBDIR%%/_distutils_hack/override.py
-%%PYTHON_SITELIBDIR%%/distutils-precedence.pth
 %%PYTHON_SITELIBDIR%%/sage-%%VER%%-py%%PYTHON_VER%%.egg-info
 %%PYTHON_SITELIBDIR%%/sage/__init__.py
 %%PYTHON_SITELIBDIR%%/sage/__pycache__/__init__.cpython-%%PYTHON_SUFFIX%%.pyc