Fix pull-suggestions diff (#158)

The diff was backwards

Signed-off-by: Phil Dibowitz <phil@ipom.com>

lib/sugarjar/commands.rb

@@ -390,7 +390,7 @@ def pullsuggestions
 
       src = "origin/#{current_branch}"
       fetch('origin')
-      diff = git('diff', src).stdout
+      diff = git('diff', "..#{src}").stdout
       return unless diff && !diff.empty?
 
       puts "Will merge the following suggestions:\n\n#{diff}"