After bootstrapping with a custom ensembe-branch, config-get no longer works.

Also affects other commands:

2011-09-09 23:45:49,582: hook.executor@DEBUG: Running hook: /var/lib/ensemble/units/mysql-4/formula/hooks/shared-db-relation-changed
2011-09-09 23:45:49,743: unit.hook.api@INFO: HOOK: shared-db-relation-changed fired.
2011-09-09 23:45:49,907: unit.hook.api@INFO: mysql - shared-db: Relation CHANGED
2011-09-09 23:45:49,977: hook.output@ERROR: Traceback (most recent call last):
  File "/usr/local/bin/relation-get", line 7, in <module>
    execfile(__file__)
  File "/usr/lib/ensemble/ensemble/bin/relation-get", line 8, in <module>
    from ensemble.hooks.commands import relation_get
ImportError: No module named ensemble.hooks.commands

2011-09-09 23:45:49,980: hook.output@DEBUG: hook shared-db-relation-changed exited, exit code Traceback (most recent call last):
Failure: ensemble.errors.FormulaInvocationError: Error processing '/var/lib/ensemble/units/mysql-4/formula/hooks/shared-db-relation-changed': exit code 1.

that seems strange.. i've use this functionality all the time to deploy formulas.. which published branch on lp is being used?

Originally hit this when using lp:~andreserl/+junk/ensemble-cloud-init, but bootstrapping a fresh environment with ensemble-branch pointing to lp:ensemble results in the same.

Looks like the custom branch is cloned to /usr/lib/ensemble/ensemble but this is missing from $ENSEMBLE_PYTHONPATH during execution of the hooks.

the sys.path replacement is borken since it bypasses the setuptools magic against develop eggs.. nixing it and restoring the sys.path extension usage that was previously here, with preferential treatment of the ensemble-python-path var over sys.path to ensure dev installations take precendence over a sys package.