Bug 37244: Facets should not impact library pulldown.

Bug 37244: Facets should not impact library pulldown.

When parsing the branch limits the regular expression matches
parameters that contains the substring "branch:" rather than the prefix
"^branch:". Consequently, both prefixes homebranch: and holdingbranch:
triggers the branch limit.

Test plan:

- Activate the system preference  IntranetAddMastheadLibraryPulldown.
- In staff interface:
  - Perform a catalogue search (e.g. "book").
  - Click on a facet for holding library or home library
    (e.g. "Fairview").
  - Click on the "more options" icon in the search box and make sure
    that "All libraries" is selected.
- Activate the system preference  OpacAddMastheadLibraryPulldown
- In opac:
  - Perform a catalogue search (e.g. "book").
  - Click on a facet for holding library or home library
    (e.g. "Fairview").
  - Make sure "All libraries" is still selected in the dropdown next
    to the search input.

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>