This happens on Jenkins:
https://integration.wikimedia.org/ci/job/mwext-mw-selenium/5536/consoleFull
As well as locally.
It seems to have started happening with this run:
https://integration.wikimedia.org/ci/job/mwext-mw-selenium/5535/consoleFull
The previous one was fine:
https://integration.wikimedia.org/ci/job/mwext-mw-selenium/5534/consoleFull
The Ruby dependencies seem to have changed between those two runs.
**Packages seen in 5534 and missing from 5535:**
blankslate 3.1.3
colorize 0.7.7
parslet 1.7.1
csscss 1.3.3
**Packages seen in 5535 and not seen in 5534:**
tins 1.6.0
**Packages with different versions between 5534 and 5535:**
unf_ext 0.0.7.2 (5534) unf_ext 0.0.7.1 (5535)
parser 2.2.2.6 (5534) parser 2.2.3.0 (5535)
**selenium-webdriver 2.50.0 (5534) selenium-webdriver 2.49.0 (5535)**
domain_name 0.5.20160128 (5534) domain_name 0.5.25 (5535)
rubocop 0.34.2 (5534) rubocop 0.35.1 (5535)