Fix adaptation of gauge temporal validity The necessity to update validity implies the new value has to cascade through to referencing columns. Because measurements falling into the validity of a new version might have been already imported, a deadlock situation might occur with the CHECK constraint on gauge_measurements preventing an update of validity and the exclusion constraint on gauges preventing the insertion of a new version before the update. Thus, the exclusion constraint is now deferred and cannot longer be used with ON CONFLICT in the INSERT statement. Gauge measurements matching the validity of a new gauge version are now 'moved' to that new version before the validity of the old version is adapted.

teichmann@intevation.de = sascha.teichmann@intevation.de
bernhard.reiter@intevation.de = bernhard@intevation.de