diff --git a/src/python/pants/bin/engine_initializer.py b/src/python/pants/bin/engine_initializer.py
index 53a8677e0c4c..3b3867361545 100644
--- a/src/python/pants/bin/engine_initializer.py
+++ b/src/python/pants/bin/engine_initializer.py
@@ -154,6 +154,9 @@ def setup_legacy_graph(pants_ignore_patterns,
     if not build_file_aliases:
       build_file_aliases = EngineInitializer.get_default_build_file_aliases()
 
+    if not rules:
+      rules = []
+
     symbol_table = LegacySymbolTable(build_file_aliases)
 
     project_tree = FileSystemProjectTree(build_root, pants_ignore_patterns)
@@ -174,8 +177,6 @@ def setup_legacy_graph(pants_ignore_patterns,
 
     # Create a Scheduler containing graph and filesystem tasks, with no installed goals. The
     # LegacyBuildGraph will explicitly request the products it needs.
-    if not rules:
-      rules = []
     tasks = (
       create_legacy_graph_tasks(symbol_table) +
       create_fs_rules() +
diff --git a/src/python/pants/build_graph/build_configuration.py b/src/python/pants/build_graph/build_configuration.py
index bcc463e41fdb..0c1d1d88b971 100644
--- a/src/python/pants/build_graph/build_configuration.py
+++ b/src/python/pants/build_graph/build_configuration.py
@@ -139,7 +139,7 @@ def register_rules(self, rules):
     """
 
     if not isinstance(rules, Iterable):
-      raise TypeError('The rules must be an iterable, given {}'.format(rules))
+      raise TypeError('The rules must be an iterable, given {!r}'.format(rules))
     self._rules.extend(rules)
 
   def rules(self):