checkout: document bug where delayed checkout counts entries twice

At the end of a `git checkout <pathspec>` operation, git reports how
many paths were checked out with a message like "Updated N paths from
the index". However, entries that end up on the delayed checkout queue
(as requested by a long-running process filter) get counted twice,
producing a wrong number in the final report. We will fix this bug in an
upcoming commit. For now, only document/demonstrate it with a
test_expect_failure.

Signed-off-by: Matheus Tavares <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: matheustavares

t/t0021-conversion.sh

@@ -1132,4 +1132,26 @@ do
 	'
 done
 
+test_expect_failure PERL 'delayed checkout correctly reports the number of updated entries' '
+	rm -rf repo &&
+	git init repo &&
+	(
+		cd repo &&
+		git config filter.delay.process "../rot13-filter.pl delayed.log clean smudge delay" &&
+		git config filter.delay.required true &&
+
+		echo "*.a filter=delay" >.gitattributes &&
+		echo a >test-delay10.a &&
+		echo a >test-delay11.a &&
+		git add . &&
+		git commit -m files &&
+
+		rm *.a &&
+		git checkout . 2>err &&
+		grep "IN: smudge test-delay10.a .* \\[DELAYED\\]" delayed.log &&
+		grep "IN: smudge test-delay11.a .* \\[DELAYED\\]" delayed.log &&
+		grep "Updated 2 paths from the index" err
+	)
+'
+
 test_done