Summary:
Two changes here:
- Remove dead Jenkins related code which is no longer relevant.
- Support `arc diff --preview`. Currently it doesn't work because a step which applies a diff assumes that a revision has been created. Which in case of `--preview` isn't. Therefore diff can't be applied and validation fails. Solution is to use `--nocommit` because for validation purposes performing a commit isn't necessary.
Test Plan:
- Current changes are submitted using `arc diff --preview`.
- All the pre-commit verification tests passed.
Reviewers: kradhakrishnan, sdong
Reviewed By: sdong
Subscribers: leveldb, andrewkr, jtolmer, dhruba
Differential Revision: https://reviews.facebook.net/D59571