only save a checkpoint at the end if something changed
only save a checkpoint at the end if something changed

git-svn-id: c1f8a8ec0b3bb2e99ab3413722f81f687760e79c@807360 13f79535-47bb-0310-9956-ffa450edef68

KlausTrainer/bigcouch,breezjw/bigcouch,bittorrent/bigcouch,georgemarshall/bigcouch,andrejb/cloudant_bigcouch,cloudant/bigcouch,cloudant/bigcouch,cloudant/bigcouch,linearregression/bigcouch,benoitc/couchit_experiment,fkaempfer/couchdb,PerilousApricot/bigcouch,breezjw/bigcouch,linearregression/bigcouch,davidcoallier/bigcouch,PerilousApricot/bigcouch,georgemarshall/bigcouch,benoitc/couchit_experiment,fkaempfer/couchdb,kofron/bigcouch,andrejb/cloudant_bigcouch,Gussy/bigcouch,breezjw/bigcouch,Asquera/bigcouch,andrejb/cloudant_bigcouch,andrejb/cloudant_bigcouch,Gussy/bigcouch,breezjw/bigcouch,davidcoallier/bigcouch,linearregression/bigcouch,benoitc/bigcouch,kofron/bigcouch,Gussy/bigcouch,bittorrent/bigcouch,breezjw/bigcouch,andrejb/cloudant_bigcouch,andrejb/cloudant_bigcouch,benoitc/bigcouch,davidcoallier/bigcouch,Asquera/bigcouch,georgemarshall/bigcouch,bittorrent/bigcouch,kofron/bigcouch,benoitc/bigcouch,georgemarshall/bigcouch,fkaempfer/couchdb,bittorrent/bigcouch,fkaempfer/couchdb,benoitc/couchit_experiment,davidcoallier/bigcouch,bittorrent/bigcouch,bittorrent/bigcouch,breezjw/bigcouch,davidcoallier/bigcouch,cloudant/bigcouch,linearregression/bigcouch,KlausTrainer/bigcouch,PerilousApricot/bigcouch,KlausTrainer/bigcouch,davidcoallier/bigcouch,cloudant/bigcouch,georgemarshall/bigcouch,PerilousApricot/bigcouch,Asquera/bigcouch,PerilousApricot/bigcouch,Gussy/bigcouch,georgemarshall/bigcouch,cloudant/bigcouch,benoitc/couchit_experiment,benoitc/bigcouch,linearregression/bigcouch,Asquera/bigcouch,kofron/bigcouch,Asquera/bigcouch,linearregression/bigcouch,kofron/bigcouch,linearregression/bigcouch,benoitc/bigcouch,andrejb/cloudant_bigcouch,fkaempfer/couchdb,KlausTrainer/bigcouch,Asquera/bigcouch,Gussy/bigcouch,benoitc/bigcouch,KlausTrainer/bigcouch,benoitc/couchit_experiment,KlausTrainer/bigcouch,fkaempfer/couchdb,kofron/bigcouch,Gussy/bigcouch,PerilousApricot/bigcouch,cloudant/bigcouch