[Koha] OPAC holdings table in 18.11 shows   instead of blank

[Mark Alexander]

Excerpts from Mark Alexander's message of 2018-12-22 11:56:33 -0500:
> In the OPAC, when looking at the MARC view for an item, there is a
> table at the bottom of the page showing some holding information.
> Those table fields that used to be blank in 18.05 are now displaying
> as " " (without the quotes) in 18.11.

After some searching, I believe this may be related to bug 13618.
I also looked at 21947, but that seems like a different issue
related to the changes for 13618.