Backward migration fails on segmentation fault when using RC2

I have been testing using RC2 by freezing this tag:

rake rails:freeze:edge TAG=rel_1-2-0_RC2

This morning, I tried to run a backward migration (-1 from current version), and Ruby barfed on a segmentation fault. Can anyone else see/try this?

$ rake migrate VERSION=13 (in /Users/lori/Projects/workspace/eTriever)

ruby(12541) malloc: *** Deallocation of a pointer not malloced: 0x1481038; This could be a double free(), or free() called with the middle of an allocated block; Try setting environment variable MallocHelp to see tools to help debug

ruby(12541) malloc: *** Deallocation of a pointer not malloced: 0x146f130; This could be a double free(), or free() called with the middle of an allocated block; Try setting environment variable MallocHelp to see tools to help debug

ruby(12541) malloc: *** Deallocation of a pointer not malloced: 0x10001; This could be a double free(), or free() called with the middle of an allocated block; Try setting environment variable MallocHelp to see tools to help debug

/Users/lori/Projects/workspace/eTriever/config/…/vendor/rails/activerecord/lib/…/…/activesupport/lib/active_support/dependencies.rb:322: [BUG] Segmentation fault

ruby 1.8.4 (2005-12-24) [i686-darwin8.5.1]