I saw in #604918 that /etc/profile is deliberately not treated as a conffile. Is there any way to get the new version installed on package upgrade, other than an external configuration management system such as Ansible?
The way /etc/profile is handled changed slightly in version 6.10, one year and a half after the bug you mention. Now, if you did not modify your /etc/profile file, it will be updated to the new default. If you are curious about how it's done, see update_to_current_default() function in the postinst. If you did modify it, ansible would be appropriate. Thanks.
