[qam] test fails in firefox_mhtml
openQA test in scenario sle-12-SP4-Desktop-DVD-Updates-x86_64-qam-regression-firefox-SLED@64bit fails in
Fails since (at least) Build 20181129-1
Last good: 20181128-1 (or more recent)
It seems that the unmht plugin cannot be found on firefox extensions anymore.
Always latest result in this scenario: latest