for drush 6.2.0, when running:
drush pm-updatecode --version-control=svn --svnsync --svncommit
on a drupal 7 site that only needs module updates, drush will properly commit the changes to svn as expected:
Project committed to Subversion successfully
however, if the site has a core update, drush will report:
No valid version control or backup engine found (the --version-control option was set to "svn").
and fail. does anyone have any idea why this is occurring, or what i should do to fix it?