devel/py-importlib-metadata: Fix circular dependency problem

... introduced by USE_PYTHON=pep517.

PR:		269363
Reported by:	John Hein <jcfyecrayz@liamekaens.com>

devel/py-importlib-metadata/Makefile

 PORTNAME=	importlib-metadata
-PORTVERSION=	6.0.0
+DISTVERSION=	6.0.0
+PORTREVISION=	1
 CATEGORIES=	devel
 MASTER_SITES=	PYPI
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
@@ -18,7 +19,7 @@ BUILD_DEPENDS=	${PYTHON_PKGNAMEPREFIX}setuptools>=56:devel/py-setuptools@${PY_FL
 RUN_DEPENDS=	${PYTHON_PKGNAMEPREFIX}zipp>=0.5:devel/py-zipp@${PY_FLAVOR}
 
 USES=		python:3.6+
-USE_PYTHON=	pep517 autoplist pytest
+USE_PYTHON=	distutils autoplist pytest
 
 NO_ARCH=	yes
 
@@ -28,4 +29,10 @@ NO_ARCH=	yes
 RUN_DEPENDS+=	${PYTHON_PKGNAMEPREFIX}typing-extensions>=3.6.4:devel/py-typing-extensions@${PY_FLAVOR}
 .endif
 
+pre-configure: # importlib-metadata introduces circular dependency when built with USE_PYTHON=pep517, see bug#269363
+	@( \
+		${ECHO} "from setuptools import setup" && \
+		${ECHO} "setup()" \
+	) > ${WRKSRC}/setup.py
+
 .include <bsd.port.post.mk>