While working on T161697 I have noticed that we did not upgrade WebdriverIO in a long time. We are currently using version 4.6.2. Our tests work fine up until version 4.7.1. Since version 4.8.0 our tests break because wdio tries to open http://127.0.0.1:8080/index.php... instead of http://127.0.0.1:8080/w/index.php... (please notice missing /w).
/w is configured in [[ https://phabricator.wikimedia.org/source/mediawiki/browse/master/tests/selenium/wdio.conf.js;858067fec39ffb88371fc936a40e4f88e0606ec4$123 | wdio.conf.js ]]
Commits v4.7.1...v4.8.0
Maybe this has caused the problem: make url act like url.resolve - closes #1946