create local prod branch if it doesn't exist and land the user on that. also...

create local prod branch if it doesn't exist and land the user on that.  also only try to delete local train- branch if it *does* exist.

scripts/merge_train.sh

@@ -11,9 +11,16 @@ git fetch origin
 TRAIN=`git branch -a | grep remotes/origin/train | sed -e 's/^.*train-\(.*\)$/\1/' | sort -n | tail -1`
 echo "Merging train ($TRAIN) into production" 
 
-git checkout remotes/origin/prod
+git checkout -B prod remotes/origin/prod
 git merge --no-ff remotes/origin/train-$TRAIN -m "integrating train $TRAIN"
-git branch -D train-$TRAIN
+
+# now delete the local train branch if it exists
+LOCAL_TRAIN_BRANCH=`git branch | fgrep train-$TRAIN`
+if [ "x${LOCAL_TRAIN_BRANCH}" == "xtrain-${TRAIN}" ] ; then
+    echo "deleting local branch: train-$TRAIN"
+    git branch -D train-$TRAIN
+fi
+
 git tag train-$TRAIN
 
 echo "All done!  Now you should delete the remote train, and push your changes"