t6423: add tests of dual directory rename plus add/add conflict
This is an attempt at minimalizing a testcase reported by Glen Choo
with tensorflow where merge-ort would report an assertion failure:
Assertion failed: (ci->filemask == 2 || ci->filemask == 4), function apply_directory_rename_modifications, file merge-ort.c, line 2410
reversing the direction of the merge provides a different error:
error: cache entry has null sha1: ...
fatal: unable to write .git/index
so we add testcases for both. With these new testcases, the
recursive strategy differs in that it returns the latter error for
both merge directions.
These testcases are somehow a little different than Glen's original
tensorflow testcase in that these ones trigger a bug with the recursive
algorithm whereas his testcase didn't. I figure that means these
testcases somehow manage to be more comprehensive.
Reported-by: Glen Choo <chooglen@google.com> Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>