Fix regex to strip quotations from hstore values

Previously regex did not strip quotation marks where hstore values were multi-line strings.

activerecord/lib/active_record/connection_adapters/postgresql/cast.rb

@@ -30,8 +30,8 @@ module ActiveRecord
             nil
           elsif String === string
             Hash[string.scan(HstorePair).map { |k,v|
-              v = v.upcase == 'NULL' ? nil : v.gsub(/^"(.*)"$/,'\1').gsub(/\\(.)/, '\1')
+              v = v.upcase == 'NULL' ? nil : v.gsub(/\A"(.*)"\Z/m,'\1').gsub(/\\(.)/, '\1')
-              k = k.gsub(/^"(.*)"$/,'\1').gsub(/\\(.)/, '\1')
+              k = k.gsub(/\A"(.*)"\Z/m,'\1').gsub(/\\(.)/, '\1')
               [k,v]
             }]
           else

activerecord/test/cases/adapters/postgresql/hstore_test.rb

@@ -189,6 +189,10 @@ class PostgresqlHstoreTest < ActiveRecord::TestCase
     assert_cycle('ca' => 'cà', 'ac' => 'àc')
   end
 
+  def test_multiline
+    assert_cycle("a\nb" => "c\nd")
+  end
+
   private
   def assert_cycle hash
     # test creation