In our setup (as an open source project) we often get differentials created with base commits which do not exist in upstream. As a result using arc patch often fails, even worse, in a non-recoverable way as --reject is passed to git apply. In a patch fails to cleanly apply it is hard to continue the work-flow and manually correct the merge conflicts.

A short comment now. Thank you for the very detailed reply.

Reproduced on

OK -- I made a new ec2 instance with the phabricator marketplace image to make the install easier. Updated to the latest stable and could still reproduce this. I don't know why the commit branches are saying that it is branched because I git reset --hard origin/stable on all the branches. I repeat -- this is a 100% fresh machine with the latest stable channel fetched from the phacility repos.

I will use a completely clean build tonight and reproduce this but the code hasn't changed since 2015.

This is documented in the userguide.

We are still occasionally running into this problem. A queuing system which ensures some kind of fairness would be really useful for us and others in the situation where demand is much greater than the builder resources. (A similar sentiment to T11153#180635)

Thanks for these suggestions. We only had one CI machine so these kinds of concerns about parallelism are not important for us. I enabled the options that you suggested.

Thanks for the lightning response!