largefiles: use clearer debug messages in actions In overridecalculateupdates(), 'g' (get) actions may be converted into other actions. In most of these cases, it does not make sense to keep the action's message. For example, 'remote created' does not make sense for an 'r' (remove) action.

largefiles: don't clobber merge action message with user message The message in the action is used for debugging and should not be the same as the question presented to the user. Use a different variable for the user message, so the 'msg' variable already in scope does not get overwritten.