The Sign-offs order from the "Optional Sign-Off Checklist" changes after each page refresh

[Softvision-RemusDranca]

[Affected versions]:

• Firefox Release 66.0.4 and above
• Chrome 74.0. and up

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• Have an "Ready for Sign-Off" experiment created on the "https://stage.experimenter.nonprod.dataops.mozgcp.net/" website.
• You are logged with your LDAP account on Experimenter stage website.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites and navigate to "https://stage.experimenter.nonprod.dataops.mozgcp.net/".
2. Open the experiment from prerequisites.
3. Refresh the page and observe the Sign-offs order from the "Optional Sign-Off Checklist" section.

[Expected result]:

• The Sign-offs order is the same.

[Actual result]:

• The Sign-offs order changes after each page refresh.

[Notes]:

• Attached is a screen recording of the issue:

[jaredlockhart]

@tiftran I think if you just wrap the sets in sorted(set(....)) that should be an easy fix.

[tiftran]

@jaredkerim will do, was along the lines of what I was thinking of as well

[Softvision-RemusDranca]

I have verified this issue and is no longer reproducible on Experimenter stage "https://stage.experimenter.nonprod.dataops.mozgcp.net/" website after the v2.28.1 stage deployment. Tested on Windows 10x64, Mac 10.14 and Arch Linux 4.16.6 x64.