linux-image-generic : Depends: linux-image-4.15.0-37-generic but it is not installable

[hackeron]

I'm building a Ubuntu Server in a chroot with:
$ debootstrap --arch amd64 bionic /mnt/ubuntu

Once inside the chroot I run apt-get install linux-image-generic grub-pc - this was working correctly earlier today (and the many times I did this in the past few months) but at the moment I get the following:

```
Reading package lists...
Building dependency tree...
Reading state information...
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-image-generic : Depends: linux-image-4.15.0-37-generic but it is not installable
                       Recommends: thermald but it is not going to be installed
```

My sources.list look like this:

```
###### Ubuntu Main Repos
deb http://archive.ubuntu.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ bionic main restricted universe multiverse

###### Ubuntu Update Repos
deb http://archive.ubuntu.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse

###### Ubuntu Partner Repo
deb http://archive.canonical.com/ubuntu bionic partner
deb-src http://archive.canonical.com/ubuntu bionic partner
```

Any ideas?
---
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
DistroRelease: Ubuntu 18.04
Package: linux (not installed)
ProcCpuinfoMinimal: Error: [Errno 2] No such file or directory: '/proc/cpuinfo'
ProcEnviron: Error: [Errno 2] No such file or directory: '/proc/11605/environ'
Tags: bionic
Uname: Linux 4.17.1-smos x86_64
UnreportableReason: The running kernel is not an Ubuntu kernel
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

_MarkForUpload: True

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1795936

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[hackeron (hackeron)]

As a workaround, removing the -proposed repositories from the sources.list file fixes the issue.

[hackeron (hackeron)]

??

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]