git-p4: test and document --use-client-spec

The depot path is required, even with this option.  Make sure
git-p4 fails and exits with non-zero.

Contents in the specified depot path will be rearranged according
to the client spec.  Test this and add a note in the docs.

Leave an XXX suggesting that this is somewhat confusing behavior
that might be good to fix later.

Function stripRepoPath() looks at self.useClientSpec.  Make sure
this is set both for command-line option --use-client-spec and
for configuration variable git-p4.useClientSpec.  Test this.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9806-git-p4-options.sh

@@ -117,6 +117,52 @@ test_expect_success 'clone --keep-path' '
 	)
 '
 
+# clone --use-client-spec must still specify a depot path
+# if given, it should rearrange files according to client spec
+# when it has view lines that match the depot path
+# XXX: should clone/sync just use the client spec exactly, rather
+# than needing depot paths?
+test_expect_success 'clone --use-client-spec' '
+	(
+		# big usage message
+		exec >/dev/null &&
+		test_must_fail "$GITP4" clone --dest="$git" --use-client-spec
+	) &&
+	cli2="$TRASH_DIRECTORY/cli2" &&
+	mkdir -p "$cli2" &&
+	test_when_finished "rmdir \"$cli2\"" &&
+	(
+		cd "$cli2" &&
+		p4 client -i <<-EOF
+		Client: client2
+		Description: client2
+		Root: $cli2
+		View: //depot/sub/... //client2/bus/...
+		EOF
+	) &&
+	P4CLIENT=client2 &&
+	test_when_finished cleanup_git &&
+	"$GITP4" clone --dest="$git" --use-client-spec //depot/... &&
+	(
+		cd "$git" &&
+		test_path_is_file bus/dir/f4 &&
+		test_path_is_file file1
+	) &&
+	cleanup_git &&
+
+	# same thing again, this time with variable instead of option
+	mkdir "$git" &&
+	(
+		cd "$git" &&
+		git init &&
+		git config git-p4.useClientSpec true &&
+		"$GITP4" sync //depot/... &&
+		git checkout -b master p4/master &&
+		test_path_is_file bus/dir/f4 &&
+		test_path_is_file file1
+	)
+'
+
 test_expect_success 'kill p4d' '
 	kill_p4d
 '