r17294: Make the code a little cleaner. Instead of using the two

r17294: Make the code a little cleaner. Instead of using the two
calls make it :

become_root_uid_only()
operation
unbecome_root_uid_only()

saving errno across the second call. Most of our internal
change calls can be replaced with these simple calls.

Jeremy
(This used to be commit 4143aa83c029848d8ec741d9218b3fa6e3fd28dd)