[Re-Opened] Github status updates failing intermittently

We are keeping this issue open on reports of intermittent (but ongoing) failures to receive Github status updates. We have not identified a root cause but are addressing customer issues individually as we continue to monitor and investigate.

Re-opening this incident from yesterday, THU, APR 14, since we are receiving more reports this morning:

> We are getting reports of Github status updates not arriving at Github for repos that have been fine in this regard for a long time. We are noticing an uptick in background job failures responsible for these status updates. In most cases, these failures resolve immediately by re-trying them. But some fail a few times before succeeding. We suspect there's an issue with the Github API (though not according to https://www.githubstatus.com/), or an isolated issue between coveralls.io and github.com, that's resulting in behavior like rate limiting. There is no known basis for actual rate limiting, but this is the effect.
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> Please know that any failing status updates will be retried in exponential back-off fashion (so they should eventually succeed) and that we are monitoring closely and will take any action we can to improve things.