To reproduce:
1. Create a CL that needs a rebaseline;
2. Run webkit-patch rebaseline-cl
3. Change the CL description (or rebaseline, etc.)
4. After all jobs finish, run webkit-patch rebaseline-cl again.

Expected: step 4 should use the results of finished jobs.

Actual: step 4 schedules new jobs, not using the finished results.

The current result is because gerrit creates a new patch set when CL description is changed. Gerrit is smart to reuse trybot results of previous patch sets for later patch sets created by description change, rebaseline, etc. that don't have actual code changes.

Rebaseline-cl should use the same gerrit rule to reuse trybot results across patch sets.