Code i have that compiles against HADOOP 2.4 doesn't build against trunk as someone took away DFSConfigKeys.DFS_NAMENODE_USER_NAME_KEY -apparently in
I know the name was obsolete, but anyone who has compiled code using that reference
rather than cutting and pasting in the string is going to find their code doesn't work.
More subtly: that will lead to a link exception trying to run that code on a 2.5+ cluster.
This is a regression: the old names need to go back in, even if they refer to the new names and are marked as deprecated