tests: add test-
issue3084.t cases for 'changed but same' as for 'unchanged'
Use suffix -same for cases where file changed but content is the same - that is
the case where manifestmerge doesn't detect that a file is unchanged.
(The suffix -id is already used for cases where the file didn't change - that
is the trivial case where manifestmerge detects that the file is unchanged.)
These new tests are good but the results are bad. There shouldn't be any merge
conflicts or prompts when one side didn't change.