brew-pull: Don't pipe diff stats through the pager

Pass the `--no-pager` flag to git when grabbing a diff summary for a patch as
there is no good reason to invoke a pager for ~2-10 lines that the user must
then exit manually.

Library/Contributions/cmds/brew-pull.rb

@@ -71,7 +71,7 @@ ARGV.named.each do|arg|
   end
 
   ohai 'Patch changed:'
-  safe_system 'git', 'diff', "#{revision}..", '--stat'
+  safe_system 'git', '--no-pager', 'diff', "#{revision}..", '--stat'
 
   if ARGV.include? '--install'
     `git diff #{revision}.. --name-status`.each_line do |line|