[Backport 8.x] Backport #3507 - Strip out new facet-only request keys

app/models/blacklight/facet_paginator.rb

@@ -16,7 +16,7 @@ class FacetPaginator
     # and need to make them accessible in a list so we can easily
     # strip em out before redirecting to catalog/index.
     mattr_accessor :request_keys do
-      { sort: :'facet.sort', page: :'facet.page', prefix: :'facet.prefix' }
+      { sort: :'facet.sort', page: :'facet.page', prefix: :'facet.prefix', fragment: :query_fragment, only: :only_values }
     end
 
     attr_reader :offset, :limit, :sort, :prefix

spec/features/facets_spec.rb

@@ -125,6 +125,17 @@
         expect(page).to have_link 'Tibetan language'
         expect(page).to have_css 'a.facet-select', count: 1
       end
+
+      it 'allows the user to filter more than once', :js do
+        visit '/catalog/facet/subject_ssim'
+        expect(page).to have_no_link 'Old age' # This is on the second page of facet values
+        expect(page).to have_css 'a.facet-select', count: 20
+
+        fill_in 'facet_suggest_subject_ssim', with: "ag"
+
+        expect(page).to have_link 'Old age'
+        expect(page).to have_link('Old age', href: '/?f%5Bsubject_ssim%5D%5B%5D=Old+age')
+      end
     end
   end
 end