Submit repo task IDs

[Aleksey Shipilev]

Hi,

Current submit repo job IDs are rather confusing. For example, for a given branch, I have got five IDs:

[Mach5] mach5-one-shade-JDK-8215724-20190108-1643-17048: PASSED
[Mach5] mach5-one-shade-JDK-8215724-20190108-2239-17125: PASSED
[Mach5] mach5-one-shade-JDK-8215724-20190109-0216-17166: PASSED
[Mach5] mach5-one-shade-JDK-8215724-20190109-0913-17241: PASSED
[Mach5] mach5-one-shade-JDK-8215724-20190109-1210-17278: PASSED

Yet, none of this tells me what exactly was being tested. Were they the restarts on the existing
state of the branches? Were they my own pushes to the branch? The dates are not very conclusive
either: they are the times submit picked up my change, not when I have pushed?

There is a simple (I think) solution here: add the Mercurial changeset id to the jdk-submit task ID.
Then I can cross-reference with current state of jdk-submit and see what was tested. For example:

[Mach5] mach5-one-shade-JDK-8215724-a0fe11b61b94-17278

Also, I don't think it is useful to have timestamp in there, and it only adds the noise? Whatever
the value is at the end (17278, is this internal job ID?) might be enough to disambiguate different
jobs.

Thanks,
-Aleksey