--- a
+++ b/hooks/pre-revprop-change.tmpl
@@ -0,0 +1,66 @@
+#!/bin/sh
+
+# PRE-REVPROP-CHANGE HOOK
+#
+# The pre-revprop-change hook is invoked before a revision property
+# is added, modified or deleted.  Subversion runs this hook by invoking
+# a program (script, executable, binary, etc.) named 'pre-revprop-change'
+# (for which this file is a template), with the following ordered
+# arguments:
+#
+#   [1] REPOS-PATH   (the path to this repository)
+#   [2] REVISION     (the revision being tweaked)
+#   [3] USER         (the username of the person tweaking the property)
+#   [4] PROPNAME     (the property being set on the revision)
+#   [5] ACTION       (the property is being 'A'dded, 'M'odified, or 'D'eleted)
+#
+#   [STDIN] PROPVAL  ** the new property value is passed via STDIN.
+#
+# If the hook program exits with success, the propchange happens; but
+# if it exits with failure (non-zero), the propchange doesn't happen.
+# The hook program can use the 'svnlook' utility to examine the 
+# existing value of the revision property.
+#
+# WARNING: unlike other hooks, this hook MUST exist for revision
+# properties to be changed.  If the hook does not exist, Subversion 
+# will behave as if the hook were present, but failed.  The reason
+# for this is that revision properties are UNVERSIONED, meaning that
+# a successful propchange is destructive;  the old value is gone
+# forever.  We recommend the hook back up the old value somewhere.
+#
+# On a Unix system, the normal procedure is to have 'pre-revprop-change'
+# invoke other programs to do the real work, though it may do the
+# work itself too.
+#
+# Note that 'pre-revprop-change' must be executable by the user(s) who will
+# invoke it (typically the user httpd runs as), and that user must
+# have filesystem-level permission to access the repository.
+#
+# On a Windows system, you should name the hook program
+# 'pre-revprop-change.bat' or 'pre-revprop-change.exe',
+# but the basic idea is the same.
+#
+# The hook program typically does not inherit the environment of
+# its parent process.  For example, a common problem is for the
+# PATH environment variable to not be set to its usual value, so
+# that subprograms fail to launch unless invoked via absolute path.
+# If you're having unexpected problems with a hook program, the
+# culprit may be unusual (or missing) environment variables.
+# 
+# Here is an example hook script, for a Unix /bin/sh interpreter.
+# For more examples and pre-written hooks, see those in
+# the Subversion repository at
+# http://svn.apache.org/repos/asf/subversion/trunk/tools/hook-scripts/ and
+# http://svn.apache.org/repos/asf/subversion/trunk/contrib/hook-scripts/
+
+
+REPOS="$1"
+REV="$2"
+USER="$3"
+PROPNAME="$4"
+ACTION="$5"
+
+if [ "$ACTION" = "M" -a "$PROPNAME" = "svn:log" ]; then exit 0; fi
+
+echo "Changing revision properties other than svn:log is prohibited" >&2
+exit 1