ets-berkeley-edu/calcentral — pull request #2123 by raydavis (2014-02-13 21:47:33+00:00)
Title: CLC-3273 Do not treat Canvas existence checks as unexpected errors

https://jira.ets.berkeley.edu/jira/browse/CLC-3273

When Canvas proxy code was moved to the new ProxyError/Exception mechanism, we missed treating 404 statuses as expected, cacheable results of existence checks. That floods the delayed-cache-cleaner with unnecessary expirations and Canvas with unnecessary re-requests.