Node builds failing with ENOENT on node_modules/.staging

We’re seeing all node builds fail in multiple repos at the npm install step where something seems to be looking for a node_modules/.staging folder that isn’t there. This has just started in the last few hours. Here’s an example error message (though there are hundreds of these per build):

npm WARN tar ENOENT: no such file or directory, open '/home/travis/build/mantacode/fe-directory/node_modules/.staging/yargs-08d4e68f/'

Link to a couple projects where this is happening:

Possibly this is an npm issue though I was not able to reproduce it locally.

Update: I have debugged one of these builds and tried things like

rm -rf package-lock.json && npm install

npm cache clean -f && npm install

npm i -g npm@latest && npm install

I have also tried clearing all build caches for this repo, but I am continuing to see the same errors regardless.

We added a github key and things have started working, but what happened? Did github invalidate keys? Did travis lose them? We didn’t change anything in these repos and they suddenly started failing.