Non-variable passed by reference warning caused by _pm_get_update_info() for disabled modules

When Drupal 7's "Check for updates of disabled modules and themes" option is checked (on admin/reports/updates/settings), and i run drush upc, i receive, after the normal output of the command:

Strict warning: Only variables should be passed by reference in [error]
_pm_get_update_info() (line 71 of
/home/ben/workspace/drush/commands/pm/update_info/drupal_7.inc).

for each of the disabled modules in my installation.

adding --debug didn't turn up much of interest, only:
WD php: Notice: Undefined index: version in drush_get_projects() [notice]
(line 369 of /home/ben/workspace/drush/commands/pm/pm.drush.inc).
[8.18 sec, 26.26 MB]