Do not process appending to HAML template variable

in the alias processor. Should fix #168

lib/brakeman/processors/haml_template_processor.rb

@@ -74,7 +74,8 @@ class Brakeman::HamlTemplateProcessor < Brakeman::TemplateProcessor
       res
 
       #_hamlout.buffer <<
-      #This seems to be used rarely, but directly appends args to output buffer
+      #This seems to be used rarely, but directly appends args to output buffer.
+      #Has something to do with values of blocks?
     elsif sexp? target and method == :<< and is_buffer_target? target
       @inside_concat = true
       out = exp.arglist[1] = process(exp.arglist[1])

lib/brakeman/processors/template_alias_processor.rb

@@ -96,11 +96,17 @@ class Brakeman::TemplateAliasProcessor < Brakeman::AliasProcessor
     false
   end
 
+  #Ignore `<<` calls on template variables which are used by the templating
+  #library (HAML, ERB, etc.)
   def find_push_target exp
     if sexp? exp
       if exp.node_type == :lvar and (exp.value == :_buf or exp.value == :_erbout)
         return nil
       elsif exp.node_type == :ivar and exp.value == :@output_buffer
+        return nil
+      elsif exp.node_type == :call and exp.target.node_type == :call and
+        exp.target.method == :_hamlout and exp.method == :buffer
+
         return nil
       end
     end