Fix render_config_file with_section_content to handle dup sections

Since duplicate sections are allowed within openstack conf files,
need to be able to handle them in some cases.  The first case of
this is in network where the ml2 conf is including the openvswitch
conf within it and there are a couple dup sections.  This
allows the spec tests to handle those cases.

Change-Id: I8d2733a248a6a13ab87c286ff620c71955726f86
Closes-Bug: #1444696

libraries/matchers.rb

@@ -11,10 +11,20 @@ if defined?(ChefSpec)
   # option1 = value1
   # option2 = value2
   # [section2]
-  # option1 = value2
+  # option3 = value3
+  #
+  # Example file content with dup sections:
+  #
+  # [section1]
+  # option1 = value1
+  # option2 = value2
+  # [section2]
+  # option3 = value3
+  # [section1]
+  # option4 = value4
   #
   # Example custom matcher that can be called in other
-  # dependends cookbooks.
+  # cookbooks.
   #
   # render_config_file(path).with_section_content(
   #   'section1', 'option1 = value1')
@@ -47,17 +57,17 @@ if defined?(ChefSpec)
       end
 
       def get_section_content(content, section)
-        match = false
+        within_section = false
         section_content = ''
         content.split("\n").each do |line|
           if section?(line, section)
-            match = true
+            within_section = true
             next
           end
 
-          section_content << "#{line}\n" if match == true && !section?(line)
-
-          break if match == true && section?(line)
+          start_of_new_section = section?(line)
+          section_content << "#{line}\n" if within_section && !start_of_new_section
+          within_section = false if start_of_new_section
         end
         section_content
       end