my rationale was that precision is not important there. What difference does it make if it is 65% or 67%?

It may not be important, but it's nice to have. We were instructed to incrementally increase experimental traffic. I'd like to do 10% every step, but the imprecise slider makes that difficult.

The builder list for a master in the migration console has precise values for experimental percentage. Since it "doesn't make a difference", why not round the values to the nearest 10%?

SG

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/9ecb59112b928fdc7e2134c5a7de01184558017c

commit 9ecb59112b928fdc7e2134c5a7de01184558017c
Author: Nodir Turakulov <nodir@google.com>
Date: Mon Feb 12 23:51:19 2018

[luci-migration] change exp percentage with 10% increments

Make UI less confusing by preventing setting experiment percentage to values
that are not divisable by 10.

Bug:  811390 
Change-Id: I0ae29e6a9bd4d44240c9f8b73ab3a8095884990d
Reviewed-on: https://chromium-review.googlesource.com/915026
Commit-Queue: Nodir Turakulov <nodir@chromium.org>
Reviewed-by: Jao-ke Chin-Lee <jchinlee@chromium.org>

[modify] https://crrev.com/9ecb59112b928fdc7e2134c5a7de01184558017c/go/src/infra/appengine/luci-migration/app/templates/pages/builder.html
[modify] https://crrev.com/9ecb59112b928fdc7e2134c5a7de01184558017c/go/src/infra/appengine/luci-migration/app/builder_test.go
[modify] https://crrev.com/9ecb59112b928fdc7e2134c5a7de01184558017c/go/src/infra/appengine/luci-migration/app/builder.go

try it out!

ummm, #4 didn't fix the issue I had filed

The original title of this bug was what I was requesting. And it would still be nice to have. But I can do without, so you can wontfix it.

ok, I assumed Description field fully describes the bug and Summary summarizes the Description.