Can it be that you have upgraded not only openacs, but as well aolserver to the very latest version (4.5.2). There is a rather new commit introducing the renamings:
https://groups.google.com/forum/?fromgroups#!msg/aolserver-commits/XfhVZhUnYwo/HhB2hrCxqAgJ
The problem might already come from acs-tcl/tcl/util-diff-procs.tcl, which does a "package req struct::list"
I would recommend to give aolserver 4.5.1 a try
-gustaf