Would it help the diagnosis if the GitException message included the message from the causing exception, as in throw new GitException("Could not checkout " + ref + ", " + e.getMessage(), e); ?

Or should some upper level method already be peeking "inside" the exception and displaying more information if there is a causing exception?

I'm not sure yet which policy to adopt. I'm investigating on some odd issue, hope to get a better diagnostic

https://code.google.com/p/guava-libraries/wiki/ThrowablesExplained ?

This is not about finding a nice way to propagate the exception, but to understand circumstances such issue occurs and better handle it from a functional point of view - or even better: prevent it.

I agree that we want to understand the conditions which cause the failures and handle them or prevent them.

Wouldn't it help with the diagnosis if the exception e were provided to the user while we're trying to learn how to prevent exception e from happening?

I wonder if not displaying the cause exception is another unhealthy side effect of the changes I allowed through in June 2014 around use of AbortException. Refer to 1c1bb6 for that code change. I submitted a placeholder bug JENKINS-26255 to remind me that it seems like previously clear exception cases have become less clear.