Bug 12593: search facets die with regex error if biblio has square brackets in fields

Bug 12593: search facets die with regex error if biblio has square brackets in fields

It's quite common to have [something] within facet data, and it produces following error:

Unmatched [ in regex; marked by <-- HERE in m/^[ <-- HERE

This problem was intoduced in Bug 12151 but is trivial to fix.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Good catch.

To test:
- Created a bibliographic record, linked to an authority record (personal name). Did a search that returned the author as a facet.
- Added a [ symbol to the author name.
- Repeated the search
=> FAIL: "Unmatched [ in regex; marked by <-- HERE in m/^[ <-- HERE"
- Apply the patch
- Retry the search
=> SUCCESS: No error, bracket shows correctly.

Passes koha-qa.pl too.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>