TC 8.0.5 and issue with SVN subrepos with Mercurial

I upgraded to TC 8.0.5 today and everythin seemed to go fine until I tried to actually do a build. My setup is a not very complicated but there are a couple of svn subrepos. My .hgsub looks like this:

vendor/boost/boost-svn = [svn]http://svn.boost.org/svn/boost/tags/release/Boost_1_55_0
vendor/googletest/googletest-svn = [svn]http://googletest.googlecode.com/svn/trunk

Previously, this worked fine. Today, however, I get this message:

Failed to build patch for build #578 {build id=1652}, VCS root: "vcs-root" {instance id=7, parent internal id=5, parent id=vcs_root, description: "mercurial: ssh://hg@hghost/project"}, due to error: 'hg --config ui.interactive=False clone --pull -U [svn]http://svn.boost.org/svn/boost/tags/release/Boost_1_55_0 hg_8312069480279456015' command failed.

Why on earth is TeamCity trying to use hg to do a SVN checkout? Is there some setting that didn't translate over?