alter order of unmerged_commits_matching_query to do cheap calculations first
alter order of unmerged_commits_matching_query to do cheap calculations first

Signed-off-by: Andi Studer <da3644e9b28f42f78599d2f727c41a08b714a603@fundingcircle.com>

iainbeeston/shipment_tracker,iainbeeston/shipment_tracker,iainbeeston/shipment_tracker,FundingCircle/shipment_tracker,FundingCircle/shipment_tracker,iainbeeston/shipment_tracker,FundingCircle/shipment_tracker,FundingCircle/shipment_tracker