Cache the value of safe_message

Also, just for extra paranoia, only call safe_message once in the
decorator methods

Adds specs to make sure it still works

app/decorators/commit_decorator.rb

@@ -16,13 +16,15 @@ class CommitDecorator < ApplicationDecorator
   # In case this first line is longer than 80 characters, it is cut off
   # after 70 characters and ellipses (`&hellp;`) are appended.
   def title
-    return no_commit_message if safe_message.blank?
+    title = safe_message
 
-    title_end = safe_message.index(/\n/)
-    if (!title_end && safe_message.length > 80) || (title_end && title_end > 80)
-      safe_message[0..69] << "&hellip;".html_safe
+    return no_commit_message if title.blank?
+
+    title_end = title.index(/\n/)
+    if (!title_end && title.length > 80) || (title_end && title_end > 80)
+      title[0..69] << "&hellip;".html_safe
     else
-      safe_message.split(/\n/, 2).first
+      title.split(/\n/, 2).first
     end
   end
 
@@ -30,11 +32,13 @@ class CommitDecorator < ApplicationDecorator
   #
   # cut off, ellipses (`&hellp;`) are prepended to the commit message.
   def description
-    title_end = safe_message.index(/\n/)
-    if (!title_end && safe_message.length > 80) || (title_end && title_end > 80)
-      "&hellip;".html_safe << safe_message[70..-1]
+    description = safe_message
+
+    title_end = description.index(/\n/)
+    if (!title_end && description.length > 80) || (title_end && title_end > 80)
+      "&hellip;".html_safe << description[70..-1]
     else
-      safe_message.split(/\n/, 2)[1].try(:chomp)
+      description.split(/\n/, 2)[1].try(:chomp)
     end
   end
 

app/models/commit.rb

@@ -107,7 +107,7 @@ class Commit
   end
 
   def safe_message
-    utf8 message
+    @safe_message ||= utf8 message
   end
 
   def created_at