diff --git a/dvc/graph/commit.py b/dvc/graph/commit.py
index 6cce7dd03..dab354ce5 100644
--- a/dvc/graph/commit.py
+++ b/dvc/graph/commit.py
@@ -39,16 +39,18 @@ class Commit(object):
         if self._branch_tips:
             branch_text = 'Branch tips: {}\n'.format(', '.join(self._branch_tips))
 
-        metric_text = ''
-        if self._is_target and self._target_metric:
-            metric_text = '\nTarget metric: {}'.format(self._target_metric)
-            if self._target_metric_delta is not None:
-                metric_text += ' ({:+f})'.format(self._target_metric_delta)
-
         if self._is_collapsed:
-            return branch_text + self.COLLAPSED_TEXT + metric_text
+            return branch_text + self.COLLAPSED_TEXT + self._text_metrics_line()
 
-        return branch_text + self._comment[:self.TEXT_LIMIT] + metric_text + '\n' + self.hash
+        return branch_text + self._comment[:self.TEXT_LIMIT] + self._text_metrics_line() + '\n' + self.hash
+
+    def _text_metrics_line(self):
+        result = ''
+        if self._is_target and self._target_metric:
+            result = '\nTarget metric: {}'.format(self._target_metric)
+            if self._target_metric_delta is not None:
+                result += ' ({:+f})'.format(self._target_metric_delta)
+        return result
 
     @property
     def is_repro(self):
diff --git a/dvc/graph/workflow.py b/dvc/graph/workflow.py
index 4c72fdd67..f88c1a0d3 100644
--- a/dvc/graph/workflow.py
+++ b/dvc/graph/workflow.py
@@ -31,10 +31,8 @@ class Workflow(object):
             if p not in self._edges:
                 self._edges[p] = set()
             self._edges[p].add(commit.hash)
-
-        if commit.hash not in self._back_edges:
-            self._back_edges[commit.hash] = set()
-        for p in commit.parent_hashes:
+            if commit.hash not in self._back_edges:
+                self._back_edges[commit.hash] = set()
             self._back_edges[commit.hash].add(p)
 
         if not commit.parent_hashes: