move updateDatasetUser past the file updates

it apparently causes new datafiles, which don't have create dates to
start to be persisted, cause a failure with an sql insert to the dataset
table with a null createdate. Moving it back to this location assures
the datafiles have create dates and avoids the exception. It's not clear
to me why trying to get the authenticatedUser in the updateDatasetUser()
call causes this.

src/main/java/edu/harvard/iq/dataverse/engine/command/impl/UpdateDatasetVersionCommand.java

@@ -129,8 +129,7 @@ public Dataset execute(CommandContext ctxt) throws CommandException {
         }
         //Get or create (currently only when called with fmVarMet != null) a new edit version
         DatasetVersion editVersion = theDataset.getOrCreateEditVersion(fmVarMet);
-        //Update the DatasetUser (which merges it into the context)
-        updateDatasetUser(ctxt);
+
 
         //Will throw an IllegalCommandException if a system metadatablock is changed and the appropriate key is not supplied.
         checkSystemMetadataKeyIfNeeded(editVersion,persistedVersion);
@@ -261,7 +260,8 @@ public Dataset execute(CommandContext ctxt) throws CommandException {
 
             theDataset.setModificationTime(getTimestamp());
 
-
+            //Update the DatasetUser (which merges it into the context)
+            updateDatasetUser(ctxt);
 
             if (clone != null) {
                 AuthenticatedUser au = (AuthenticatedUser) getUser();