Fixes issues with the tf.train.Saver in the 0.7.0 release.

1. The cifar10_train.py example model was emitting warnings, because of
   non-Variable objects in the `tf.moving_average_variables()`
   collection. This change fixes that by only adding `Variable`-typed
   objects to that collection in `moving_averages.py` (which better
   agrees with the definition in `tf.GraphKeys.MOVING_AVERAGES_VARIABLES`).

2. Saver.save() now calls `tf.gfile.MakeDirs(os.path.dirname(save_path))`,
   which fails if `save_path` does not contain a directory component.
   This change fixes the implementation of `tf.gfile.MakeDirs('')` to be a
   no-op (which better matches the internal library that it is shadowing).

Fixes #1123. Fixes #1135.
Change: 114895020

tensorflow/python/platform/default/_gfile.py

@@ -282,17 +282,16 @@ def MakeDirs(path, mode=0o755):  # pylint: disable=invalid-name
   """Recursively create the directory "path" with the given mode.
 
   Args:
-    path: The directory path
+    path: The directory path.
     mode: The file mode for the created directories
 
-  Returns:
-    None
-
-
   Raises:
     OSError: if the path already exists
   """
-  os.makedirs(path, mode)
+  # NOTE(mrry): MakeDirs("") should be a no-op to match other
+  # implementations of tf.gfile.
+  if path:
+    os.makedirs(path, mode)
 
 
 def RmDir(directory):   # pylint: disable=invalid-name

tensorflow/python/platform/default/gfile_test.py

@@ -17,6 +17,7 @@
 from __future__ import division
 from __future__ import print_function
 
+import contextlib
 import os
 import shutil
 import time
@@ -148,6 +149,22 @@ def testMkDirsGlobAndRmDirs(self):
     gfile.DeleteRecursively(self.tmp + "test_dir")
     self.assertFalse(gfile.Exists(self.tmp + "test_dir"))
 
+  @contextlib.contextmanager
+  def _working_directory(self, wd):
+    original_cwd = os.getcwd()
+    os.chdir(wd)
+    try:
+      yield
+    finally:
+      os.chdir(original_cwd)
+
+  def testMakeDirsWithEmptyString(self):
+    gfile.MakeDirs(self.tmp + "test_dir")
+    with self._working_directory(self.tmp + "test_dir"):
+      gfile.MakeDirs("")
+    # Should succeed because MakeDirs("") is a no-op.
+    gfile.RmDir(self.tmp + "test_dir")
+
   def testErrors(self):
     self.assertRaises(
         OSError, lambda: gfile.RmDir(self.tmp + "dir_doesnt_exist"))

tensorflow/python/training/moving_averages.py

@@ -269,12 +269,14 @@ def apply(self, var_list=None):
           avg = slot_creator.create_slot(
               var, var.initialized_value(), self._name,
               colocate_with_primary=True)
+          # NOTE(mrry): We only add `tf.Variable` objects to the
+          # `MOVING_AVERAGE_VARIABLES` collection.
+          ops.add_to_collection(ops.GraphKeys.MOVING_AVERAGE_VARIABLES, var)
         else:
           avg = slot_creator.create_zeros_slot(
               var, self._name,
               colocate_with_primary=(var.op.type == "Variable"))
       self._averages[var] = avg
-      ops.add_to_collection(ops.GraphKeys.MOVING_AVERAGE_VARIABLES, var)
 
     with ops.name_scope(self._name) as scope:
       decay = ops.convert_to_tensor(self._decay, name="decay")

tensorflow/python/training/moving_averages_test.py

@@ -87,6 +87,8 @@ def _CheckDecay(self, ema, actual_decay, dim):
     avg1 = ema.average(var1)
     avg2 = ema.average(tensor2)
 
+    self.assertItemsEqual([var0, var1], tf.moving_average_variables())
+
     self.assertFalse(avg0 in tf.trainable_variables())
     self.assertFalse(avg1 in tf.trainable_variables())
     self.assertFalse(avg2 in tf.trainable_variables())