Merge pull request #2702 from takahashim/fix-string-match

fix infinite loop in String#match(arg) when arg is String

mrblib/string.rb

@@ -146,8 +146,17 @@ class String
   ##
   # ISO 15.2.10.5.27
   def match(re, &block)
+    if re.respond_to? :to_str
+      if Object.const_defined?(:Regexp)
+        r = Regexp.new(re)
+        r.match(self, &block)
+      else
+        raise NotImplementedError, "String#match needs Regexp class"
+      end
+    else
       re.match(self, &block)
     end
+  end
 end
 
 ##