frontend container: intermittent build error: unable to remove temporary directory contents

During a rebuild using the Containerfile-frontend build instructions, the following error occurred once; it hasn't happened again in a few subsequent rebuilds:

...
STEP 13/19: RUN     set -o pipefail &&         export GNUPGHOME=$(mktemp -d) &&         wget ${GROCY_RELEASE_KEY_URI} -O - | gpg --batch --import &&         git clone --branch ${GROCY_VERSION} --config advice.detachedHead=false --depth 1 "https://github.com/grocy/grocy.git" . &&         git verify-commit ${GROCY_VERSION} &&         rm -rf ${GNUPGHOME}
gpg: keybox '/tmp/tmp.GAnAnK/pubring.kbx' created
--2023-03-31 13:42:00--  https://berrnd.de/data/Bernd_Bestel.asc
Resolving berrnd.de (berrnd.de)... 185.244.195.227
Connecting to berrnd.de (berrnd.de)|185.244.195.227|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3138 (3.1K) [application/octet-stream]
Saving to: 'STDOUT'

     0K ...                                                   100%  271M=0s

2023-03-31 13:42:01 (271 MB/s) - written to stdout [3138/3138]

gpg: /tmp/tmp.GAnAnK/trustdb.gpg: trustdb created
gpg: key 71BD34C0D4891300: public key "Bernd Bestel <bernd@berrnd.de>" imported
gpg: Total number processed: 1
gpg:               imported: 1
Cloning into '.'...
gpg: Signature made Sat Nov 12 17:24:01 2022 UTC
gpg:                using RSA key 5E64333554C6C62F414F4C6771BD34C0D4891300
gpg: Good signature from "Bernd Bestel <bernd@berrnd.de>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 5E64 3335 54C6 C62F 414F  4C67 71BD 34C0 D489 1300
rm: can't remove '/tmp/tmp.GAnAnK/S.gpg-agent.ssh': No such file or directory

The build process includes the following steps:

Change into the nginx user context
Create a temporary directory to use to hold GnuPG data
Import GPG public key data for grocy
After cloning the grocy repository, verify the latest commit (implicitly using GnuPG)
Remove the temporary GnuPG data directory

It seems unusual for the temporary directory removal step to fail with that error message.

grocy / grocy-docker

frontend container: intermittent build error: unable to remove temporary directory contents #210