t9300 (fast-import): another test for the "replace root" feature

Another test for the replace root feature.  One can imagine an
implementation for which R "some/subdir" "" would free some state
associated to the subdir and leave fast-import confused.

Luckily, git's is not such an implementation.

While at it, change the previous test to use C "some/subdir" ""
instead of R (i.e., test both syntaxes).

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9300-fast-import.sh

@@ -990,11 +990,52 @@ test_expect_success \
 	COMMIT
 
 	M 040000 $branch ""
-	R "newdir" ""
+	C "newdir" ""
 	INPUT_END
 	 git fast-import <input &&
 	 git diff --exit-code branch:newdir N9'
 
+test_expect_success \
+	'N: modify subtree, extract it, and modify again' \
+	'echo hello >expect.baz &&
+	 echo hello, world >expect.qux &&
+	 git fast-import <<-SETUP_END &&
+	commit refs/heads/N10
+	committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+	data <<COMMIT
+	hello, tree
+	COMMIT
+
+	deleteall
+	M 644 inline foo/bar/baz
+	data <<EOF
+	hello
+	EOF
+	SETUP_END
+
+	 tree=$(git rev-parse --verify N10:) &&
+	 git fast-import <<-INPUT_END &&
+	commit refs/heads/N11
+	committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+	data <<COMMIT
+	copy to root by id and modify
+	COMMIT
+
+	M 040000 $tree ""
+	M 100644 inline foo/bar/qux
+	data <<EOF
+	hello, world
+	EOF
+	R "foo" ""
+	C "bar/qux" "bar/quux"
+	INPUT_END
+	 git show N11:bar/baz >actual.baz &&
+	 git show N11:bar/qux >actual.qux &&
+	 git show N11:bar/quux >actual.quux &&
+	 test_cmp expect.baz actual.baz &&
+	 test_cmp expect.qux actual.qux &&
+	 test_cmp expect.qux actual.quux'
+
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