Code review comment for lp:~wgrant/launchpad/sprbu-columns-to-sprb

I'm unsure of upload_log. Dropping this column in the future and migrating its information to SourcePackageRecipeBuildUpload seems more work than just creating the SourcePackageRecipeBuildUpload records.

We should either drop this column from the patch and create SourcePackageRecipeBuildUpload records, or add a comment stating that the column is temporary and add the needed index with "CREATE INDEX sourcepackagerecipiebuild__upload_log__idx ON SourcepackageRecipieBuild(upload_log);"