[QA] Resolving editing conflicts for jobs run via CloudBees

[Jeff Hall]

I don't see this too often, but every once in a while, browser tests run 
via CloudBees (Jenkins) will fail because of an "edit conflict".  Example[1]

This seems to be a consequence of the "Chrome version" and the "Firefox 
version" of browser tests running against the same target environment at 
the same time.

Near as I can tell, we schedule the test jobs from a template[2] so that 
they all kick off at the same times twice a day:

     <hudson.triggers.TimerTrigger>
       <spec>0 3,18 * * *</spec>
     </hudson.triggers.TimerTrigger>

In a previous position where I used Jenkins, we staggered the kick-off 
times for each individual job in order to try and avoid these type of 
conflicts.  Since I see these conflicts infrequently via the WMF 
CloudBees instance, it may not be worth the trouble of unwinding our 
current scheduling trigger, but if anyone else has brilliant ideas on 
resolving these conflicts in some other way, I'm all ears!

Thanks,

Jeff


[1] 
https://saucelabs.com/jobs/33cdfcc91a3843bc83aa5598b8e06ecf/0010screenshot.png
[2] 
https://github.com/wikimedia/mediawiki-selenium/blob/master/docs/template.md