keybase update cron job using 100% CPU

```console
$ ps auxf | grep -B6 6023
root 913 0.0 0.0 15936 2704 ? Ss 13:16 0:00 /usr/sbin/anacron -dsq
root 5914 0.0 0.0 4636 776 ? S 13:21 0:00 \_ /bin/sh -c run-parts --report /etc/cron.daily
root 5915 0.0 0.0 4528 876 ? S 13:21 0:00 \_ run-parts --report /etc/cron.daily
root 5930 0.0 0.0 4636 864 ? S 13:21 0:00 \_ /bin/sh /etc/cron.daily/keybase
root 5935 0.0 0.0 4636 1760 ? S 13:21 0:00 \_ /bin/sh /usr/bin/apt-key add -
root 6021 0.0 0.0 4636 200 ? S 13:21 0:00 \_ /bin/sh /usr/bin/apt-key add -
root 6023 67.5 1.5 156896 125952 ? RL 13:21 15:50 \_ gpg --ignore-time-conflict --no-options --no-default-keyring --homedir /tmp/apt-key-gpghome.pGsoibuAd8 --no-auto-check-trustdb --trust-model always --keyring /etc/apt/trusted.gpg --batch --import --import-options merge-only
```

Notice the fourth line of output shows that it's the keybase daily update checker that spawns this gpg line, which is using 100% of CPU for more than 20 minutes now:


Start by tracing /etc/cron.daily/keybase through /usr/bin/apt-key to the shown gpg import command, and reproduce the daily update behavior while monitoring CPU use. Done means the keybase update cron job completes without sustained excessive CPU usage; the issue does not name a test or source file to run.

Written by the indexing model from the issue text.