The integration-slave01 labs instance is running npm tests for the Collection offline content generators:
mwext-Collection-OfflineContentGenerator-bundler-npmtest
mwext-Collection-OfflineContentGenerator-latex_renderer-npmtest
mwext-Collection-OfflineContentGenerator-npmtest
The slave has been brought offline because /tmp ended up being filled. Looking at it I had files such as mw-latexer* and mw-ocg-latexer*.
They should be made temporary files or even better mocked in the unit tests :-)