sheyang, how could I modify bugdroid to accept something like this? 

You probably need to start from log_parser to recognize the new keyword (example https://codereview.chromium.org/2030003003/diff/20001/infra/services/bugdroid/log_parser.py), and pass it down to IssueTrackerManager to set send_email to False.

WIP CL at https://chromium-review.googlesource.com/c/356694/

Didn't end up getting much done with this. I believe the correct reviewer now is agable@ or mmoss@, since sheyang left Google.

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra.git/+/ba095768d776568605a29ddad503deb2ce1e184e

commit ba095768d776568605a29ddad503deb2ce1e184e
Author: Stephen Martinis <martiniss@chromium.org>
Date: Fri Aug 19 23:53:41 2016

Fix bugdroid sending email flag

Forgot to add (?m) to the beginning of the regex, which changes it to run in
"multiline" mode; see https://docs.python.org/2/library/re.html#contents-of-module-re
for more details.

BUG= 621746 

Change-Id: I78db8e0c3c52613f15b689787f59104ce7e680b0
Reviewed-on: https://chromium-review.googlesource.com/368232
Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Stephen Martinis <martiniss@chromium.org>

[modify] https://crrev.com/ba095768d776568605a29ddad503deb2ce1e184e/infra/services/bugdroid/log_parser.py
[modify] https://crrev.com/ba095768d776568605a29ddad503deb2ce1e184e/infra/services/bugdroid/test/log_parser_test.py

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra.git/+/f81ba41f36f64210d97b3c1951d2f18e4a6527bf

commit f81ba41f36f64210d97b3c1951d2f18e4a6527bf
Author: Stephen Martinis <martiniss@chromium.org>
Date: Mon Aug 22 22:29:27 2016

recipe roller: Don't send bugdroid emails for rolls

BUG= 621746 

Change-Id: I13e816aeefe14be78513435941a28772e3a767eb
Reviewed-on: https://chromium-review.googlesource.com/368096
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Erik Staab <estaab@chromium.org>
Reviewed-by: Paweł Hajdan Jr. <phajdan@google.com>

[modify] https://crrev.com/f81ba41f36f64210d97b3c1951d2f18e4a6527bf/recipes/recipe_modules/recipe_autoroller/api.py
[modify] https://crrev.com/f81ba41f36f64210d97b3c1951d2f18e4a6527bf/recipes/recipes/recipe_autoroller.expected/basic.json
[modify] https://crrev.com/f81ba41f36f64210d97b3c1951d2f18e4a6527bf/recipes/recipes/recipe_autoroller.expected/failed_upload.json
[modify] https://crrev.com/f81ba41f36f64210d97b3c1951d2f18e4a6527bf/recipes/recipes/recipe_autoroller.expected/nontrivial.json
[modify] https://crrev.com/f81ba41f36f64210d97b3c1951d2f18e4a6527bf/recipes/recipes/recipe_autoroller.expected/repo_data_trivial_closed.json
[modify] https://crrev.com/f81ba41f36f64210d97b3c1951d2f18e4a6527bf/recipes/recipes/recipe_autoroller.expected/with_auth.json

If this is really a Pri-1, find an owner and update the priority.

This is the result of a bulk edit that moved high priority available bugs to a lower priority in an attempt to be more honest with bug filers.

I fixed this.