Bug#988082: shim-signed: Fails to install on non-UEFI systems

[Tollef Fog Heen <tfheen@err.no>]

Package: shim-signed
Version: 1.34~1+deb10u1+15.4-2~deb10u1
Severity: serious
X-Debbugs-Cc: none, Tollef Fog Heen <tfheen@err.no>

Looks like postinst is poking into /sys/firmware/efi, which doesn't
exist on a non-UEFI system.

Preparing to unpack .../shim-signed_1.34~1+deb10u1+15.4-2~deb10u1_amd64.deb ...
Unpacking shim-signed:amd64 (1.34~1+deb10u1+15.4-2~deb10u1) over (1.33+15+1533136590.3beb971-7) ...
Preparing to unpack .../shim-signed-common_1.34~1+deb10u1+15.4-2~deb10u1_all.deb ...
Unpacking shim-signed-common (1.34~1+deb10u1+15.4-2~deb10u1) over (1.33+15+1533136590.3beb971-7) ...
Preparing to unpack .../shim-unsigned_15.4-3~deb10u1_amd64.deb ...
Unpacking shim-unsigned (15.4-3~deb10u1) over (15.4-2~deb10u1) ...
Setter opp shim-signed:amd64 (1.34~1+deb10u1+15.4-2~deb10u1) ...
cat: /sys/firmware/efi/fw_platform_size: No such file or directory
dpkg: error processing package shim-signed:amd64 (--configure):
 installed shim-signed:amd64 package post-installation script subprocess returned error exit status 1
Setter opp shim-signed-common (1.34~1+deb10u1+15.4-2~deb10u1) ...
No DKMS packages installed: not changing Secure Boot validation state.
Setter opp shim-unsigned (15.4-3~deb10u1) ...
Det oppsto feil ved behandling av:
 shim-signed:amd64
needrestart is being skipped since dpkg has failed
E: Sub-process /usr/bin/dpkg returned an error code (1)

(It's a fair question to ask «why are you installing it here?», in this
particular case, it's a bug, but one could very well be doing this as a
part of migrating from legacy to UEFI boot.)

-- 
Tollef Fog Heen
UNIX is user friendly, it's just picky about who its friends are