linux-modules-extra-* fails to install due to dependency on unsigned package

Several SRU tests are failing the test setup due to failure to install the modules-extra package:

* Command:
    yes "" | DEBIAN_FRONTEND=noninteractive apt-get install --yes --force-yes
    automake bison build-essential byacc flex git keyutils libacl1-dev libaio-
    dev libcap-dev libmm-dev libnuma-dev libsctp-dev libselinux1-dev libssl-
    dev libtirpc-dev pkg-config quota xfslibs-dev xfsprogs gcc linux-modules-
    extra-4.15.0-1120-aws
Exit status: 100
Duration: 0.908210039139

stdout:
Reading package lists...
Building dependency tree...
Reading state information...
xfsprogs is already the newest version (4.9.0+nmu1ubuntu2).
xfsprogs set to manually installed.
git is already the newest version (1:2.17.1-1ubuntu0.9).
git set to manually installed.
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 linux-modules-extra-4.15.0-1120-aws : Depends: linux-image-unsigned-4.15.0-1120-aws but it is not going to be installed
stderr:
W: --force-yes is deprecated, use one of the options starting with --allow instead.
E: Unable to correct problems, you have held broken packages.