[pmwiki-users] upgrade to 2.1.3 breaks preview - changesum problem?

[Bruce Files]

We just upgraded from 2.0.12 to the new 2.1.3 release.  Now the
Preview button no longer works.

We have a simple configuration.  After a little testing, I found that
everything works if we comment out this line in our local/config.php:
include_once('local/changesum.php');

Is changesum.php not compatible with the 2.1.x release?

Thanks,
Bruce