Re-run a test with changes

[slightlyoff]

Feature Request Summary

It would be a tremendous time-savings in site analysis if the "re-run test" button had a "re-run test with changes" option. This version would drop the analyst back at the test run configuration screen with all the details from the previous test pre-populated.

What's the motivation or use case for the change/feature?

For iterating on complex test configurations (e.g., writing scripts or configuring chromium trace categories), getting the same test config between runs is time consuming and error prone. Analysts can easily forget to copy/paste or reconfigure some detail between runs, and there's no easy easy way today to say "start with this run as a template", either from the test log or from the test details page.

Having the ability to start with a past run as a template for configuration and iteration would be incredibly helpful. We have this in Microsoft's internal WPT instance ("PAS"), and it's a lifesaver.

[nathanbower]

I've been dreaming of this feature. It would be a huge time savings and convenience. +100