packages: add manifest to commit for uprev_ebuild_from_pin

BUG=b:143709253
TEST=./run_tests (passes inside and outside the chroot)

Change-Id: I9185e7fffe5313dd5b446b4bdd247ffbca52adf7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2080642
Tested-by: Trent Begin <tbegin@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Trent Begin <tbegin@chromium.org>
diff --git a/service/packages_unittest.py b/service/packages_unittest.py
index 46335e1..ad4edcc 100644
--- a/service/packages_unittest.py
+++ b/service/packages_unittest.py
@@ -135,7 +135,7 @@
     mod = result.modified[0]
     self.assertEqual(mod.new_version, self.new_version,
                      'unexpected version number: %s' % mod.new_version)
-    self.assertEqual(len(mod.files), 2,
+    self.assertEqual(len(mod.files), 3,
                      'unexpected number of modified files: %s' % len(mod.files))
 
     old_ebuild_path = os.path.join(package_path,
@@ -148,6 +148,10 @@
     self.assertEqual(mod.files[0], new_ebuild_path,
                      'unexpected updated ebuild file: %s' % mod.files[1])
 
+    manifest_path = os.path.join(package_path, 'Manifest')
+    self.assertEqual(mod.files[2], manifest_path,
+                     'unexpected manifest file: %s' % mod.files[1])
+
     self.assertCommandContains(['ebuild', 'manifest'])
 
   def test_no_ebuild(self):