hpcc-systems/HPCC-Platform — pull request #1801 by jakesmith (2012-03-08 16:16:18+00:00)
Title: gh-1646 - Detect new environment cluster group changes

Use old environment to detect configuration changes.
When constructing cluster groups, either at dali startup, or when a new
environment is loaded, e.g. via updtdalienv, compare old definition with new
and active groups.
The active groups are updated only if the new group definition mismatches the
old environment definition. i.e. no update will occur, if they already match
the active group, or they match the old environment definition.

This means, that a cluster environment change will be reflected when it's
deployed or updated, but prevents rollbacks of the active groups, during an
update or restart if the environment group hasn't changed, but the active
groups have diverged from old environment, e.g. due to swaps.