Fix some old templates that abused colon as an argument separator.

This is a fallback for keyword argument parsing since this feature broke
old templates that accidentally used a colon as a filter argument
separator.

lib/liquid/variable.rb

@@ -23,9 +23,9 @@ module Liquid
         if match[2].match(/#{FilterSeparator}\s*(.*)/o)
           filters = Regexp.last_match(1).scan(FilterParser)
           filters.each do |f|
-            if matches = f.match(/\s*(\w+)(?:\s*#{FilterArgumentSeparator}(.*))?/)
+            if matches = f.match(/\s*(\w+)/)
               filtername = matches[1]
-              filterargs = matches[2].to_s.scan(/(?:\A|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o).flatten
+              filterargs = f.scan(/(?:#{FilterArgumentSeparator}|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o).flatten
               @filters << [filtername, filterargs]
             end
           end

test/liquid/variable_test.rb

@@ -113,6 +113,12 @@ class VariableTest < Test::Unit::TestCase
     assert_equal 'hello', var.name
     assert_equal [['things',["greeting: \"world\"","farewell: 'goodbye'"]]], var.filters
   end
+
+  def test_lax_filter_argument_parsing
+    var = Variable.new(%! number_of_comments | pluralize: 'comment': 'comments' !)
+    assert_equal 'number_of_comments', var.name
+    assert_equal [['pluralize',["'comment'","'comments'"]]], var.filters
+  end
 end