It appears that sha1sum in RHEL6 and older is stricter about the format it will accept when checking checksums. It expects exactly two spaces between the checksum and the filename.
So, be prepared to munge the format as necessary.
Metadata Update from @tibbs: - Issue assigned to tibbs
Metadata Update from @tibbs: - Issue tagged with: in progress
Fixed by 6198d21bc27bdca59f912b8e22903fc8b435d3bc.
Metadata Update from @tibbs: - Issue untagged with: in progress - Issue close_status updated to: Fixed - Issue status updated to: Closed (was: Open)