Bug#1025820: Bug: grub-pc 2.06-3~deb10u3 upgrade assumes /tmp is exec

[imschmeg]

Package: grub-pc
Version: 2.06-3~deb10u3

The error message during an "apt upgrade" that includes grub-pc is:

open2: exec of /tmp/grub-pc.config.ajRf2i configure 2.06-3~deb10u2
failed: Permission denied at /usr/share/perl5/Debconf/ConfModule.pm
line 59. 

The problem is that apt upgrade assumes /tmp is mounted exec.  Common
security practice is to mount /tmp noexec, which I do.

Apt install scripts could instead be executed without being exec by
passing them as a parameter to the shell command.

Also, after the error, the apt upgrade finished instead of aborting,
leaving my system in an unknown state.  I had to remount /tmp with exec
and reinstall the grub packages.

My system is:
$ uname -a
Linux lapdog 5.10.0-15mx-amd64 #1 SMP Debian 5.10.120-1~mx19+1
(2022-06-13) x86_64 GNU/Linux