Modifying author property in subversion using svn propset

In case you use multiple user names in subversion and you make a mistake and hence have to modify author property,here's the command:
svn propset svn:author 'vmaanpaa' -r53626 --revprop
but first, make sure that in you repository, i.e.
/var/repository/hooks
you have something like:
[root@svn hooks]# cat pre-revprop-change
#!/bin/sh
REPOS="$1"
REV="$2"
USER="$3"
PROPNAME="$4"
ACTION="$5"

also, this file needs to be executable by apache.