tests: unpack-trees: update to use test_i18n* functions

Use functions test_i18ncmp and test_i18ngrep to successfully pass tests
running under GETTEXT_POISON.

The output strings compared to in these test were marked for translation
in ed47fdf ("i18n: unpack-trees: mark strings for translation",
2016-04-09) and later improved in 2e3926b ("i18n: unpack-trees: avoid
substituting only a verb in sentences", 2016-05-12).

Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1011-read-tree-sparse-checkout.sh

@@ -247,7 +247,7 @@ error: The following untracked working tree files would be overwritten by checko
 Please move or remove them before you can switch branches.
 Aborting
 EOF
-	test_cmp expected actual
+	test_i18ncmp expected actual
 '
 
 test_expect_success 'checkout without --ignore-skip-worktree-bits' '

t/t3400-rebase.sh

@@ -136,8 +136,8 @@ test_expect_success 'setup: recover' '
 test_expect_success 'Show verbose error when HEAD could not be detached' '
 	>B &&
 	test_must_fail git rebase topic 2>output.err >output.out &&
-	grep "The following untracked working tree files would be overwritten by checkout:" output.err &&
-	grep B output.err
+	test_i18ngrep "The following untracked working tree files would be overwritten by checkout:" output.err &&
+	test_i18ngrep B output.err
 '
 rm -f B
 

t/t3404-rebase-interactive.sh

@@ -219,9 +219,9 @@ test_expect_success 'abort with error when new base cannot be checked out' '
 	git commit -m "remove file in base" &&
 	set_fake_editor &&
 	test_must_fail git rebase -i master > output 2>&1 &&
-	grep "The following untracked working tree files would be overwritten by checkout:" \
+	test_i18ngrep "The following untracked working tree files would be overwritten by checkout:" \
 		output &&
-	grep "file1" output &&
+	test_i18ngrep "file1" output &&
 	test_path_is_missing .git/rebase-merge &&
 	git reset --hard HEAD^
 '

t/t7607-merge-overwrite.sh

@@ -125,7 +125,7 @@ test_expect_success 'will not overwrite untracked file in leading path' '
 	cp important sub &&
 	cp important sub2 &&
 	test_must_fail git merge sub 2>out &&
-	test_cmp out expect &&
+	test_i18ncmp out expect &&
 	test_path_is_missing .git/MERGE_HEAD &&
 	test_cmp important sub &&
 	test_cmp important sub2 &&