Modifying transaction properties (svnadmin setrevprop)

For a long time I've known the rule "don't modify a transaction in a
pre-commit hook", documented in (1) and recently repeated in (2).

I was therefore surprised to read about the "svnadmin setrevprop" command
(3) in 1.9, and to see an example of modifying transaction properties in
the hook-scripts: "persist-ephemeral-txnprops.py" (4).

Are there some conditions under which it's okay to modify the transaction,
or are there only specific use-cases when this should be done?

Thanks,
- Ryan

(1)
http://svnbook.red-bean.com/en/1.8/svn.reposadmin.create.html#svn.reposadmin.create.hooks
(2) http://markmail.org/message/kmxxbk4nrvmpc66r
(3)
https://subversion.apache.org/docs/release-notes/1.9.html#svnadmin-revprop
(4)
http://svn.apache.org/viewvc/subversion/trunk/tools/hook-scripts/persist-ephemeral-txnprops.py?view=markup
Received on 2016-04-23 23:23:40 CEST