Index: moz-phab
===================================================================
--- moz-phab
+++ moz-phab
@@ -601,6 +601,7 @@
         """Validate the list of commits (from commit_stack) are ok to submit"""
         errors = []
 
+        all_reviewers = dict(granted=set(), request=set())
         for commit in commits:
             commit_errors = []
             # TODO allow NOBUG in commit message (not in arg)
@@ -611,8 +612,9 @@
             if has_arc_rejections(commit["body"]):
                 commit_errors.append("contains arc fields")
 
-            if commit["reviewers"]:
-                errors += check_for_invalid_reviewers(commit["reviewers"], self.path)
+            for group in commit["reviewers"].keys():
+                for reviewer in commit["reviewers"][group]:
+                    all_reviewers[group].add(reviewer)
 
             if commit_errors:
                 errors.append(
@@ -620,6 +622,8 @@
                     % (commit["name"], commit["title"], "\n- ".join(commit_errors))
                 )
 
+        errors.extend(check_for_invalid_reviewers(all_reviewers, self.path))
+
         if errors:
             raise Error("\n\n".join(errors))