Update to correct localManifestBranch

Change-Id: I54a4c8350181675951b5dfb0af37f4710d20aaf1
diff --git a/core/treble/build-treble.sh b/core/treble/build-treble.sh
index 22b087c..8842c1e 100755
--- a/core/treble/build-treble.sh
+++ b/core/treble/build-treble.sh
@@ -5,7 +5,7 @@
 mkdir -p release/$rom_fp/
 set -e
 
-localManifestBranch="android-9.0"
+localManifestBranch="p9.0"
 rom="bliss"
 bliss_variant=""
 bliss_variant_name=""