"Failed to set 'QT_MODULE_TO_TEST' environment variable" warning

Recently, when manually scheduling a build on coin, the message

Failed to set 'QT_MODULE_TO_TEST' environment variable. That should not happen, please contact the Coin admins and maybe try to restage your changes. 

appears. Examples were this happened are:

• http://10.212.3.36:8080/coin/integration/qt/qtwebengine/tasks/web_qt_qtwebengine_1563363087365
• http://10.212.3.36:8080/coin/integration/qt/qtbase/tasks/web_qt_qtbase_1563352853536
• http://10.212.3.36:8080/coin/integration/qt/qtdeclarative/tasks/web_qt_qtdeclarative_1563519100351