pkg: Cannot open /dev/null:No such file or directory

Hello List,

lately I ran into a serious problem installing packages in a nanoBSD
environment, in which the package repository server is "remotely" on site. The
issue as documented below occurs on both 12-STABLE r348529 and CURRENT r348600
and must have been introduced shortly, since the last known good installation
with the environment of ours was on 21st May 2019.

As far as I know,, the package installation is performed via "chroot'ed"
environment and somehow /dev/null is out of a sudden not accessible anymore
while pkg tries to delegate some output to /dev/null.

What happened here?

Kind regards and thanks in advance,

oh

[...]
All repositories are up to date.
The following 10 package(s) will be affected (of 0 checked):

New packages to be INSTALLED:
        python3: 3_3 [zeit4]
        sudo: 1.8.27_1 [zeit4]
        devcpu-data: 1.22 [zeit4]
        python36: 3.6.8_2 [zeit4]
        readline: 8.0.0 [zeit4]
        indexinfo: 0.3.1 [zeit4]
        libffi: 3.2.1_3 [zeit4]
        gettext-runtime: 0.19.8.1_2 [zeit4]
        openldap-sasl-client: 2.4.47 [zeit4]
        cyrus-sasl: 2.1.27 [zeit4]

Number of packages to be installed: 10

The process will require 129 MiB more space.
20 MiB to be downloaded.
[1/10] Fetching python3-3_3.txz: . done
[2/10] Fetching sudo-1.8.27_1.txz: .......... done
[3/10] Fetching devcpu-data-1.22.txz: .......... done
[4/10] Fetching python36-3.6.8_2.txz: .......... done
[5/10] Fetching readline-8.0.0.txz: .......... done
[6/10] Fetching indexinfo-0.3.1.txz: . done
[7/10] Fetching libffi-3.2.1_3.txz: ..... done
[8/10] Fetching gettext-runtime-0.19.8.1_2.txz: .......... done
[9/10] Fetching openldap-sasl-client-2.4.47.txz: .......... done
[10/10] Fetching cyrus-sasl-2.1.27.txz: .......... done
Checking integrity... done (0 conflicting)
[1/10] Installing indexinfo-0.3.1...
[1/10] Extracting indexinfo-0.3.1: .... done
[2/10] Installing readline-8.0.0...
[2/10] Extracting readline-8.0.0: .......... done
pkg: Cannot open /dev/null:No such file or directory
[3/10] Installing libffi-3.2.1_3...
[3/10] Extracting libffi-3.2.1_3: .......... done
pkg: Cannot open /dev/null:No such file or directory
[4/10] Installing gettext-runtime-0.19.8.1_2...
[4/10] Extracting gettext-runtime-0.19.8.1_2: .......... done
pkg: Cannot open /dev/null:No such file or directory
[5/10] Installing cyrus-sasl-2.1.27...
pkg: Cannot open /dev/null:No such file or directory