Arvados

Currently, if outputTTL is set too low and a workflow tries to use intermediate data after it has already been trashed, a-c-r may read a intermediate collection manifest successfully (before trash time) but then fail to save it later (after trash time) in a combined collection. In that case the user ends up getting a python stack trace ending in a 403 error (invalid blob signature).

a-c-r should warn the user when the duration the current workflow has been running exceeds outputTTL (this is probably a good indicator the user should increase outputTTL even if it hasn't actually broken anything yet)

a-c-r should also report a more helpful error message when it fails to create a collection due to expired blob signatures. This could be done by checking for a 403 error from the create call and/or checking the expiry times (given as hexadecimal unix times) on the blob signatures in the manifest text.