Bug 1750 - Report bor_issues_top erroneous and truncated results.

Bug 1750 - Report bor_issues_top erroneous and truncated results.

Signed-off-by: Mason James <mtj@kohaaloha.com>
TEST PLAN
---------
1) Ensure you have some checkouts
2) Home -> Reports
        -> Patrons with the most checkouts
3) Click 'Submit'
   -- you get a list
4) Click a patron name.
5) Note the borrower number.
6) In MySQL run something like:
   > UPDATE borrower SET firstname=NULL WHERE borrowernumber=####
7) Refresh the report page
   -- name goes totally blank
8) apply patch
9) Refresh the report page
   -- only first name is lost
10) run koha qa test tools

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Brendan Gallagher <bredan@bywatersolutions.com>