tests/test-gendoc-da.t

merge: drop obsolete non-linear cases from docstring table

Since 6b1fc09c699a (update: change default destination to tipmost
descendant (issue4673) (BC), 2016-02-02), non-linear updates can no
longer happen if the user doesn't specify a destination, so we can
drop these case from the table in the docstring of merge.update().

#require docutils gettext

  $ $TESTDIR/check-gendoc da
  checking for parse errors