The following revision refers to this bug:
  https://chromium.googlesource.com/infra/luci/recipes-py/+/0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07

commit 0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07
Author: Robert Iannucci <iannucci@chromium.org>
Date: Fri Dec 14 22:21:29 2018

[manual_roll] Add new manual_roll command.

This will help when preparing manual rolls. It calculates the smallest
recipes.cfg file change and writes that to disk. You can run it multiple
times in a row to walk through the rolls.

R=jchinlee@chromium.org, sergeyberezin@chromium.org

Bug:  915063 
Change-Id: Iae14a96e53bafae3c5ca68905d5d46201b4ed229
Reviewed-on: https://chromium-review.googlesource.com/c/1377619
Auto-Submit: Robbie Iannucci <iannucci@chromium.org>
Reviewed-by: Jao-ke Chin-Lee <jchinlee@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>

[modify] https://crrev.com/0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07/recipe_engine/autoroll_impl/candidate_algorithm.py
[add] https://crrev.com/0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07/recipe_engine/manual_roll.py
[modify] https://crrev.com/0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07/recipe_engine/unittests/fetch_test.py
[modify] https://crrev.com/0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07/doc/user_guide.md
[modify] https://crrev.com/0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07/recipe_engine/autoroll.py
[modify] https://crrev.com/0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07/recipe_engine/main.py
[modify] https://crrev.com/0cbbe4a2a8b0a309f08b5a5459292885e8e1ce07/recipe_engine/fetch.py