apt purge linux-modules... fails to remove system76_acpi.ko

[kjcole]

(Originally filed in 2022 in the pop repository; Issue #2704)

This happens with both generic and lowlatency kernels on every upgrade.

• Distribution: Pop!_OS 22.04 LTS

   NAME="Pop!_OS"
   VERSION="22.04 LTS"
    ID=pop
   ID_LIKE="ubuntu debian"
   PRETTY_NAME="Pop!_OS 22.04 LTS"
   VERSION_ID="22.04"
   HOME_URL="https://pop.system76.com"
   SUPPORT_URL="https://support.system76.com"
   BUG_REPORT_URL="https://github.com/pop-os/pop/issues"
   PRIVACY_POLICY_URL="https://system76.com/privacy"
   VERSION_CODENAME=jammy
   UBUNTU_CODENAME=jammy
   LOGO=distributor-logo-pop-os

• Related Application and/or Package Version : apt

    apt:
      Installed: 2.4.13
      Candidate: 2.4.13
      Version table:
     *** 2.4.13 500
            500 http://apt.pop-os.org/ubuntu jammy-updates/main amd64 Packages
            100 /var/lib/dpkg/status
         2.4.5 500
            500 http://apt.pop-os.org/ubuntu jammy/main amd64 Packages

• Related Application and/or Package Version : linux-image

    linux-image-6.8.0-48-lowlatency:
      Installed: (none)
      Candidate: 6.8.0-48.48.3~22.04.1
      Version table:
         6.8.0-48.48.3~22.04.1 500
            500 http://apt.pop-os.org/ubuntu jammy-security/main amd64 Packages
            500 http://apt.pop-os.org/ubuntu jammy-updates/main amd64 Packages

• Related Application and/or Package Version linux-modules-6.8.0-48-lowlatency

    linux-modules-6.8.0-48-lowlatency:
      Installed: (none)
      Candidate: 6.8.0-48.48.3~22.04.1
      Version table:
         6.8.0-48.48.3~22.04.1 500
            500 http://apt.pop-os.org/ubuntu jammy-security/main amd64 Packages
            500 http://apt.pop-os.org/ubuntu jammy-updates/main amd64 Packages

• Issue/Bug Description:

  apt purge linux-modules-... has been getting stuck for several versions, each time, failing to remove system76_acpi.ko

• Steps to reproduce (if you know):

    $ apt purge linux-image-6.8.0-48-lowlatency linux-modules-6.8.0-48-lowlatency
...
    Purging configuration files for linux-image-6.8.0-48-lowlatency (6.8.0-48.48.3~22.04.1) ...
    rmdir: failed to remove '/lib/modules/6.8.0-48-lowlatency': Directory not empty
    Purging configuration files for linux-modules-6.8.0-48-lowlatency (6.8.0-48.48.3~22.04.1) ...
    dpkg: warning: while removing linux-modules-6.8.0-48-lowlatency, directory '/lib/modules/6.8.
    0-48-lowlatency' not empty so not removed

    $ ls -R /lib/modules/6.8.0-48-lowlatency
    6.8.0-48-lowlatency:
    extra  updates
    
    6.8.0-48-lowlatency/extra:
    v4l2loopback.ko
    
    6.8.0-48-lowlatency/updates:
    dkms
    
    6.8.0-48-lowlatency/updates/dkms:
    system76_acpi.ko

• Expected behavior:

  The purge should recognize that /lib/modules/.../updates/dkms/system76_acpi.ko is part of the package being purged, and since the newer kernel modules library has a copy of the file, it's safe to purge it.