Arg delete + undo mangles state of a macro

Sample file (one line, cursor position on the closing paren):

fn(delete_this_word,)

macro that works: X%wdw
macro that fails: X%wdaaudw

Both macros have identical results when executed manually, but the latter one fails when executed as a macro. The only difference between the macros is the daau, which performs the arg deletion and then undoes it.
