ISO mount causes plugins to fail on filesystem package update

[dmnks]

Originally filed as RHEL-33726:

When RHEL repos are available from an ISO mount reinstalling the filesystem package shows errors:

[root@ima ~]# dnf reinstall filesystem
...
Running transaction test
Transaction test succeeded.
Running transaction
  Running scriptlet: filesystem-3.16-2.el9.x86_64                          1/1 
  Preparing        :                                                       1/1 
  Reinstalling     : filesystem-3.16-2.el9.x86_64                          1/2 
error: lsetfilecon: (29 /mnt, system_u:object_r:mnt_t:s0) Read-only file system
error: Plugin selinux: hook fsm_file_prepare failed

Error unpacking rpm package filesystem-3.16-2.el9.x86_64
  Verifying        : filesystem-3.16-2.el9.x86_64                          1/2 
  Verifying        : filesystem-3.16-2.el9.x86_64                          2/2 
Installed products updated.

Failed:
  filesystem-3.16-2.el9.x86_64           filesystem-3.16-2.el9.x86_64          

Error: Transaction failed

This came up when preparing a system for IMA which currently requires all packages to be reinstalled, in that case with the rpm-plugin-ima package installed we see:

[root@ima ~]# dnf reinstall filesystem
...
Running transaction test
Transaction test succeeded.
Running transaction
  Running scriptlet: filesystem-3.16-2.el9.x86_64                          1/1 
  Preparing        :                                                       1/1 
  Reinstalling     : filesystem-3.16-2.el9.x86_64                          1/2 
error: ima: could not apply signature on '/mnt': Read-only file system
error: Plugin ima: hook fsm_file_prepare failed
error: lsetfilecon: (29 /mnt, system_u:object_r:mnt_t:s0) Read-only file system
error: Plugin selinux: hook fsm_file_prepare failed

Error unpacking rpm package filesystem-3.16-2.el9.x86_64
  Verifying        : filesystem-3.16-2.el9.x86_64                          1/2 
  Verifying        : filesystem-3.16-2.el9.x86_64                          2/2 
Installed products updated.

Failed:
  filesystem-3.16-2.el9.x86_64           filesystem-3.16-2.el9.x86_64          

Error: Transaction failed

Thanks.