Unprivileged bootstrapping fails on Ubuntu 20.04: ERROR: Circular dependency detected #106

$ uname -a
Linux app-biip 5.4.0-107-generic #121-Ubuntu SMP Thu Mar 24 16:04:27 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

$ lsb_release -d
Description:    Ubuntu 20.04.4 LTS

$ bootstrap/bootstrap --unprivileged
===> bootstrap command: bootstrap/bootstrap --unprivileged
===> bootstrap started: Mon May  9 19:30:16 EEST 2022
Working directory is: /big/pkgsrc/work
===> running: /usr/bin/sed -e 's|@DEFAULT_INSTALL_MODE@|'0755'|' /big/pkgsrc/sysutils/install-sh/files/install-sh.in > /big/pkgsrc/work/bin/install-sh
===> running: /usr/bin/chmod +x /big/pkgsrc/work/bin/install-sh
===> building as unprivileged user s2/s2
===> Creating default mk.conf in /big/pkgsrc/work
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -d -o s2 -g s2 /big/pkgsrc/work/sbin
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -d -o s2 -g s2 /big/pkgsrc/work/share/mk
===> Bootstrapping mk-files
===> running: (cd /big/pkgsrc/pkgtools/bootstrap-mk-files/files && env CP=/usr/bin/cp  OPSYS=Linux MK_DST=/big/pkgsrc/work/share/mk ROOT_GROUP=root ROOT_USER=root SED=/usr/bin/sed SYSCONFDIR=/home/s2/pkg/etc /usr/bin/sh ./bootstrap.sh)
===> Bootstrapping bmake
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -d -o s2 -g s2 /big/pkgsrc/work/bmake
===> running: (cd /big/pkgsrc/work/bmake && /usr/bin/sh configure  --prefix=/big/pkgsrc/work --with-default-sys-path=/big/pkgsrc/work/share/mk --with-machine-arch=x86_64 )
  ...
===> running: (cd /big/pkgsrc/work/bmake && /usr/bin/sh make-bootstrap.sh)
  ...
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -c -o s2 -g s2 -m 755 /big/pkgsrc/work/bmake/bmake /big/pkgsrc/work/bin/bmake
===> Building libnbcompat
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -d -o s2 -g s2 /big/pkgsrc/work/libnbcompat
===> running: (cd /big/pkgsrc/work/libnbcompat; /usr/bin/sh ./configure  -C --prefix=/home/s2/pkg --infodir=/home/s2/pkg/info --mandir=/home/s2/pkg/man --sysconfdir=/home/s2/pkg/etc --enable-bsd-getopt --enable-db && /big/pkgsrc/work/bin/bmake  -j1)
  ...
===> Bootstrapping awk
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -d -o s2 -g s2 /big/pkgsrc/work/awk
===> running: (cd /big/pkgsrc/work/awk && /big/pkgsrc/work/bin/bmake  -j1 -f Makefile CC="cc" CFLAGS="")
  ...
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -c -o s2 -g s2 -m 755 /big/pkgsrc/work/awk/a.out /big/pkgsrc/work/bin/nawk
===> Bootstrapping pkgtools
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -d -o s2 -g s2 /big/pkgsrc/work/libarchive
===> running: (cd /big/pkgsrc/work/libarchive; env  CONFIG_SHELL=/usr/bin/sh /usr/bin/sh ./configure  --enable-static --disable-shared --disable-bsdtar --disable-bsdcpio --disable-posix-regex-lib --disable-xattr --disable-maintainer-mode --disable-acl --without-zlib --without-bz2lib --without-iconv --without-lzma --without-lzo2 --without-lz4 --without-nettle --without-openssl --without-xml2 --without-expat --without-zstd MAKE=/big/pkgsrc/work/bin/bmake && /big/pkgsrc/work/bin/bmake  -j1)
  ...
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -d -o s2 -g s2 /big/pkgsrc/work/pkg_install
===> running: (cd /big/pkgsrc/work/pkg_install; env  CPPFLAGS=' -I/big/pkgsrc/work/libnbcompat -I/big/pkgsrc/work/libarchive/libarchive' LDFLAGS=' -L/big/pkgsrc/work/libnbcompat' LIBS=' -lnbcompat' /usr/bin/sh ./configure  -C --enable-bootstrap --prefix=/home/s2/pkg --sysconfdir=/home/s2/pkg/etc --with-pkgdbdir=/home/s2/pkg/pkgdb --infodir=/home/s2/pkg/info --mandir=/home/s2/pkg/man  && STATIC_LIBARCHIVE=/big/pkgsrc/work/libarchive/.libs/libarchive.a STATIC_LIBARCHIVE_LDADD='' PKGSRC_MACHINE_ARCH=x86_64 /big/pkgsrc/work/bin/bmake  -j1)
  ...
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -c -o s2 -g s2 -m 755 /big/pkgsrc/work/pkg_install/add/pkg_add /big/pkgsrc/work/sbin/pkg_add
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -c -o s2 -g s2 -m 755 /big/pkgsrc/work/pkg_install/admin/pkg_admin /big/pkgsrc/work/sbin/pkg_admin
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -c -o s2 -g s2 -m 755 /big/pkgsrc/work/pkg_install/create/pkg_create /big/pkgsrc/work/sbin/pkg_create
===> running: /usr/bin/sh /big/pkgsrc/work/bin/install-sh -c -o s2 -g s2 -m 755 /big/pkgsrc/work/pkg_install/info/pkg_info /big/pkgsrc/work/sbin/pkg_info
===> running: (cd /big/pkgsrc/pkgtools/cwrappers && /big/pkgsrc/work/bin/bmake  MAKE_JOBS=1 PKG_COMPRESSION=none PKGSRC_KEEP_BIN_PKGS=no MAKECONF=/big/pkgsrc/work/mk.conf install)
===> Installing dependencies for cwrappers-20220403
=> Tool dependency coreutils>=5.2.1: NOT found
=> Verifying reinstall for ../../sysutils/coreutils
=> Bootstrap dependency digest>=20211023: NOT found
=> Verifying reinstall for ../../pkgtools/digest
===> Installing dependencies for digest-20220214
=> Tool dependency cwrappers>=20150314: NOT found
=> Verifying reinstall for ../../pkgtools/cwrappers
ERROR: This package has set PKG_FAIL_REASON:
ERROR: Circular dependency detected
*** Error code 1

Stop.
bmake[3]: stopped in /big/pkgsrc/pkgtools/cwrappers
*** Error code 1

Stop.
bmake[2]: stopped in /big/pkgsrc/pkgtools/digest
*** Error code 1

Stop.
bmake[1]: stopped in /big/pkgsrc/sysutils/coreutils
*** Error code 1

Stop.
bmake: stopped in /big/pkgsrc/pkgtools/cwrappers
===> exited with status 1
aborted.
$