Merge branch 'jk/test-fixes' into maint

Test fixes.

* jk/test-fixes:
  t7800: don't rely on reuse_worktree_file()
  t4018: drop "debugging" cat from hunk-header tests

t/t4018-diff-funcname.sh

@@ -106,7 +106,6 @@ do
 		result=success
 	fi
 	test_expect_$result "hunk header: $i" "
-		test_when_finished 'cat actual' &&	# for debugging only
 		git diff -U1 $i >actual &&
 		grep '@@ .* @@.*RIGHT' actual
 	"

t/t7800-difftool.sh

@@ -125,15 +125,14 @@ test_expect_success 'difftool stops on error with --trust-exit-code' '
 	test_when_finished "rm -f for-diff .git/fail-right-file" &&
 	test_when_finished "git reset -- for-diff" &&
 	write_script .git/fail-right-file <<-\EOF &&
-	echo "$2"
+	echo failed
 	exit 1
 	EOF
 	>for-diff &&
 	git add for-diff &&
-	echo file >expect &&
 	test_must_fail git difftool -y --trust-exit-code \
 		--extcmd .git/fail-right-file branch >actual &&
-	test_cmp expect actual
+	test_line_count = 1 actual
 '
 
 test_expect_success 'difftool honors exit status if command not found' '