[LP] SudoDialog.check_dependencies won't work on non-English locale

Submitted by Sean Davis @bluesabre

Assigned to Sean Davis @bluesabre

Link to original bug (#14485)

Description

From https://bugs.launchpad.net/catfish-search/+bug/1501562

See downstream bug. Basically, the pexpect integration does not work properly with non-English locales.