Merge pull request rails#34612 from utilum/bigdecimal_raises_on_comma_in_string_argument

Another Ruby 2.6 BigDecimal compatibility issue

Author: rafaelfranca

activesupport/lib/active_support/xml_mini.rb

@@ -71,7 +71,7 @@ def content_type
             begin
               BigDecimal(number)
             rescue ArgumentError
-              BigDecimal("0")
+              BigDecimal(number.to_f.to_s)
             end
           else
             BigDecimal(number)