scripts/oe-build-perf-report: Avoid buildstats warning
When a comparision branch is set we see warnings. If two branches are used,
look for buildstats information from both to avoid this kind of warning:
INFO: Parsing buildstats from 'refs/notes/buildstats/perf-centos7.yoctoproject.org/master-next/qemux86'
WARNING: Buildstats not found for perf-centos7.yoctoproject.org/master/qemux86/
56808-g08220028e52992dcba667fc97bf3afe8be1949fb/0
WARNING: Buildstats not found for perf-centos7.yoctoproject.org/master/qemux86/
56808-g08220028e52992dcba667fc97bf3afe8be1949fb/1
INFO: Buildstats were missing for some test runs, please run 'git fetch origin refs/notes/buildstats/perf-centos7.yoctoproject.org/master-next/qemux86:refs/notes/buildstats/perf-centos7.yoctoproject.org/master-next/qemux86' and try again
(the warning is due to stats being looked for in both branches, choose
the other branch and different warnings would be shown)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
