emerge's confmem already provides similar functionality which is a little
safer.
svn path=/main/trunk/; revision=12705
# Ignore a version that is identical to the previously merged version,
# even though it is different from the current user modified version
+# Note that emerge already has a similar feature enabled by default,
+# which can be disabled by the emerge --noconfmem option.
# (yes or no)
-ignore-previously-merged=yes
+ignore-previously-merged=no
# Per-session log file of changes made to configuration files
#log-file=/var/log/dispatch-conf.log