This isn't needed anymore as this was merged with Debian by Steve:

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multipath-tools (0.8.3-1ubuntu1) focal; urgency=low

  * Merge from Debian unstable.  Remaining changes:
    - Stop producing udebs on i386 where we no longer have d-i or a kernel.
    - Fix debian/rules to not explode when building without udebs on i386.
    - Don't build the multipath-tools binary package on i386; we only want
      kpartx.
    - d/control:
      - multipath-udeb: add sg3-udeb Depends
    - d/rules: Move udev rules to priority 95, because rules that load modules
      should be >90.
    - d/multipath-tools.preinst: modprobe dm-multipath; This will make sure
      that multipathd will be able to start.
    - Split kpartx initramfs bits into kpartx-boot for dmraid (LP 941874)
      - d/initramfs/kpartx.hook
      - d/kpartx-boot.postinst
      - d/kpartx-boot.postrm
      - d/control: Add kpartx-boot package for dmraid
      - d/rules: Install kpartx initramfs hook
      - d/kpartx.install: install all arch /lib* kpartx udev rules
    - patches to multipath source
      - d/p/1000--set-umask-in-multipathd.patch: Set umask in multipathd.
      - d/p/kpartx_more_loopback_fixes.patch: fix loopback mounted
        files some more: since we stat() the loopback device node, we can't rely
        on S_ISREG() tests to handle this case, and should look at the device
        itself instead. (LP 1543430)
      - d/p/enable-find-multipaths.patch: re-enable find_multipaths
        by default -- see the removed 'add_find-multipaths.patch' (LP 1463046)
   - multipath initramfs fixes for booting from multipathed devices
      - d/initramfs/hooks: also copy wwids file on the installed system to
        ensure all paths come up on boot. (LP 1479929)
      - d/initramfs/hooks: install multipathd and required directories.
      - d/initramfs/hooks: copy multipath udev rules to initramfs
      - d/initramfs/hooks: do not copy kpartx rules to initramfs
      - d/initramfs/local-bottom: remember to stop multipathd.
      - d/initramfs/local-premount: wait for udev to settle before the call to
        resolve_device() in local_mount_root(), so the by-uuid/ symlinks have a
        chance to be updated by the multipath udev rules (LP 1503286).
      - d/initramfs/local-premount: Run multipath with -B so not to assign names
        nor change /etc/multipath/bindings during initramfs (LP 1561103)
      - d/rules: install d/initramfs/local-bottom
      - d/rules: install d/initramfs/local-premount
   - Disable -fexceptions on multipath-udeb (LP 1489379): the flag causes
     libchecktur.so to link with libgcc_s.so.1 (even with -static-libgcc),
     which is not available in the installer environment.
     - d/p/disable-fexceptions-udeb.patch: conditionally disable -fexceptions
       with CFLAGS_DISABLE_FEXCEPTIONS.
     - d/rules: set CFLAGS_DISABLE_FEXCEPTIONS to build multipath-udeb.
     - d/p/disable-fexceptions-udeb.patch: conditionally disable -fexceptions
       with CFLAGS_DISABLE_FEXCEPTIONS.
     - d/rules: set CFLAGS_DISABLE_FEXCEPTIONS to build multipath-udeb.
   - Remove d/initramfs/local-top (redundant with other initramfs scripts):
     - init-top: take over loading modules (dm-multipath and SCSI device
       handlers); move the missing dm-emc there (now scsi-dh-emc;
       see BTS 567014).
     - d/rules: do not install local-top anymore.
     - remove d/initramfs/local-top
    - Fixes typo in package description (availibility -> availability)
      (LP 1231182)
    - debian/initramfs/local-bottom: wait for the multipathd unix socket
      to close, so to avoid multipathd.socket unit failure. (LP 1682178)
    - debian/initramfs/hooks: Add dm-queue-length: users may want to change
      from the default selector and should be able to do so. (LP 1673350)
    - d/p/kpartx-Improve-finding-loopback-device-by-file.patch: Improve
      finding loopback devices (LP 1747044)
    - d/p/kpartx-print-loop-deleted-to-stdout-not-stderr.patch: Print loop
      deleted message to stdout again, not stderr; to fix autopkgtest
    - Install friendly names multipath.conf by default, instead of
      generating it in every installer.
    - Use stable wwn-* names in autopkgtest that work with or without
      friendly names, as scsi-${DM_NAME} is not a stable symlink name.
    - Do not attempt to start multipath-tools in containers, should switch
      for on-demand udev/socket based activation in the future. LP 1823093
    - Adjust initramfs integration for new udev rules
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I'll run my tests in his upload, its pretty much the same anyways.