apt-get dist-upgrade hangs at "update-rc.d: using dependency based boot sequencing"

As per the subject, I'm doing an apt-get dist-upgrade on a BBB and it
seems to hang (after doing a lot of upgrading) after saying the
following:-

    ...
    ...
    ...
    Installing new version of config file /etc/modprobe.d/fbdev-blacklist.conf ...
    Installing new version of config file /etc/udev/udev.conf ...
    Adding group `input' (GID 118) ...
    Done.
    update-rc.d: using dependency based boot sequencing

Is it just taking a long time to do the next thing in the upgrade
sequence or has something got stuck?

It was some sort of dpkg utility that had got stuck. I killed it and
I'm now re-running 'apt-get update' and 'apt-get upgrade' to sort out
all the dependencies. It seems to be getting there slowly.