* This commit rearranges some of the logic branches to protect
against an unusual case of having two holding statements with
the same start value, but one being open-ended and one not.
* The logic in get_combined_holdings() was a little sloppy and
repeated some steps unnecessarily. This cleans things up.
See the test case in the previous commit for more clarity.
Signed-off-by: Dan Wells <dbw2@calvin.edu> Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>