Major Description
In general /etc/default/<component> settings are supposed to be there for daemon configuration (since daemons typically lack any other means of setting up an environment for themselves).
We've been piggybacking on those for the client side of things, but it does cause troubles with certain user-level settings sometimes. The correct solution here would be to completely decouple daemon setting from the client ones (as BIGTOP-492 suggests) but until this happens we have to workaround.
Removing HBase client's dependency on /etc/default/hadoop seems to be harmless and it lets users tweak the environment.