Show the error if a job prepare script fails.

Change-Id: Ibf0510cd87d4198b3c873be4dc8df352b8df3aad
Make dependency resolution recursive.

Change-Id: If434e01a72b1681c3048b4fb7c58ff31d6b949ee
Merge "Make dependency resolution recursive."
Merge "Show the error if a job prepare script fails."