pkg/55372: PKGSRC_MKREPRO=yes from scratch causes circular dependency

[ryo%tetera.org@localhost]

>Number:         55372
>Category:       pkg
>Synopsis:       PKGSRC_MKREPRO=yes from scratch causes circular dependency
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jun 12 14:55:00 +0000 2020
>Originator:     Ryo ONODERA
>Release:        NetBSD 9.99.65
>Organization:
Ryo ONODERA // ryo%tetera.org@localhost
PGP fingerprint = 82A2 DC91 76E0 A10A 8ABB  FD1B F404 27FA C7D1 15F3
>Environment:
	
	
System: NetBSD brownie 9.99.65 NetBSD 9.99.65 (DTRACE7) #3: Fri Jun 12 13:16:17 JST 2020 ryoon@brownie:/usr/world/9.99/amd64/obj/sys/arch/amd64/compile/DTRACE7 amd64
Architecture: x86_64
Machine: amd64
>Description:
When no pkgsrc package is installed on NetBSD system,
if /etc/mk.conf has PKGSRC_MKREPRO=yes,
building any packages causes circular dependency error.

For example,
ryoon@brownie: /usr/pkgsrc/shells/zsh
$ make PKGSRC_MKREPRO=yes
=> Bootstrap dependency digest>=20010302: NOT found
=> Verifying reinstall for ../../pkgtools/digest
===> Skipping vulnerability checks.
WARNING: No /var/db/pkg/pkg-vulnerabilities file found.
WARNING: To fix run: `/usr/sbin/pkg_admin -K /var/db/pkg fetch-pkg-vulnerabilities'.
===> Installing dependencies for digest-20190127
=> Build dependency cwrappers>=20150314: NOT found
=> Verifying reinstall for ../../pkgtools/cwrappers
===> Skipping vulnerability checks.
WARNING: No /var/db/pkg/pkg-vulnerabilities file found.
WARNING: To fix run: `/usr/sbin/pkg_admin -K /var/db/pkg fetch-pkg-vulnerabilities'.
===> Installing dependencies for cwrappers-20180325
=> Build 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.
make[3]: stopped in /usr/pkgsrc/pkgtools/cwrappers
*** Error code 1

Stop.
make[2]: stopped in /usr/pkgsrc/pkgtools/cwrappers
*** Error code 1

Stop.
make[1]: stopped in /usr/pkgsrc/pkgtools/digest
*** Error code 1

Stop.
make: stopped in /usr/pkgsrc/shells/zsh

>How-To-Repeat:
	
# pkg_delete '*'
# cd /usr/pkgsrc/shells/zsh
# make PKGSRC_MKREPRO=yes install

>Fix:
	
I have no idea.

>Unformatted: