ReceiveCommitsAdvertiseRefsHook: Request reviewer field

This is necessary to check draft visibility. It should have been added
at the same time as I177109ed9c.

Change-Id: I04574080793255df18eff1323203195ca9d1d17e

gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommitsAdvertiseRefsHook.java

@@ -109,6 +109,7 @@ public class ReceiveCommitsAdvertiseRefsHook implements AdvertiseRefsHook {
       ImmutableSet.of(
           // Required for ChangeIsVisibleToPrdicate.
           ChangeField.CHANGE.getName(),
+          ChangeField.REVIEWER.getName(),
           // Required during advertiseOpenChanges.
           ChangeField.PATCH_SET.getName());