Bug 10795: Improvements for GetOpenIssue in C4::Circulation

Bug 10795: Improvements for GetOpenIssue in C4::Circulation

This patch adds some improvements for the routine GetOpenIssue().
Now, it verifies if the parameter is given (if not it returns undef)
and it returns $sth->fetchrow_hashref() instead of a $issue.

To test:
prove t/db_dependent/Circulation_issue.t
t/db_dependent/Circulation_issue.t .. ok
All tests successful.
Files=1, Tests=16,  2 wallclock secs ( 0.06 usr  0.01 sys +  1.09 cusr  0.07 csys =  1.23 CPU)
Result: PASS

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Comment: Same situation as the one noted in comment of
Bug 10683, test fails unless there is an issuingrule
All, All with 1 as renewals allowed.

With that condition, it succeeds

No koha-qa errors

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>