USE_RC_SUBR collides with WRKSRC when Forgejo/Gitea archive extracts to ${PORTNAME}/

[tuaris]

I'm having a tough time trying to figure this out. I currently have a workaround in place with post-extract, but maybe there is a better way to handle it?

When a port's source archive extracts to a directory named ${PORTNAME} and the port also uses USE_RC_SUBR=${PORTNAME}, the build fails during the configure phase with:

/bin/sh: cannot create /path/to/work/${PORTNAME}: Is a directory

Here's my Makefile:

PORTNAME=    securedmarc
DISTVERSIONPREFIX=    v
DISTVERSION=    0.1.0
CATEGORIES=    mail
MASTER_SITES=    https://pacyworld.dev/securemessage/${PORTNAME}/archive/${DISTVERSIONFULL}${EXTRACT_SUFX}?dummy=/
DISTFILES=    ${DISTNAME}${EXTRACT_SUFX}

MAINTAINER=   xxxxxxxxx
COMMENT=    RFC 7489 DMARC policy evaluation milter (high-performance Zig implementation)
WWW=        https://pacyworld.dev/securemessage/securedmarc

LICENSE=    BSD2CLAUSE
LICENSE_FILE=    ${WRKSRC}/LICENSE

USES=        zig:015

post-extract:
    @${MV} ${WRKDIR}/${PORTNAME} ${WRKSRC}

USE_RC_SUBR=    securedmarc

USERS=        _dmarc
GROUPS=        _dmarc

PLIST_FILES=    bin/securedmarc \
        "@sample ${ETCDIR}/securedmarc.conf.sample"

post-install:
    @${MKDIR} ${STAGEDIR}${ETCDIR}
    ${INSTALL_DATA} ${WRKSRC}/config/securedmarc.conf.sample \
        ${STAGEDIR}${ETCDIR}/securedmarc.conf.sample

.include <bsd.port.mk>