Automated tests for adding a certificate to Pidgin stopped working

They still work on our stable branch but they stopped failing on devel between:

• https://jenkins.tails.boum.org/job/build_Tails_ISO_devel/3025/ → https://jenkins.tails.boum.org/view/RM/job/test_Tails_ISO_devel/1350/
• https://jenkins.tails.boum.org/job/build_Tails_ISO_devel/3040/ → https://jenkins.tails.boum.org/view/RM/job/test_Tails_ISO_devel/1351/

Feature Branch: test/15762-update-pidgin-certificate

Related issues

• Blocks #13241 (closed)

Original created by @intrigeri on 15762 (Redmine)