Fix --one_shot for remote file system. (#4909)

Fixes uploads to TensorBoard.dev in the case where the logdir was not local.

Author: bileschi

tensorboard/uploader/BUILD

@@ -76,6 +76,7 @@ py_library(
         "//tensorboard:expect_absl_logging_installed",
         "//tensorboard:expect_grpc_installed",
         "//tensorboard:program",
+        "//tensorboard/compat:tensorflow",
         "//tensorboard/plugins:base_plugin",
         "//tensorboard/uploader/proto:protos_all_py_pb2_grpc",
     ],

tensorboard/uploader/uploader_subcommand.py

@@ -23,6 +23,7 @@
 
 from absl import logging
 import grpc
+from tensorboard.compat import tf
 
 from tensorboard.uploader.proto import experiment_pb2
 from tensorboard.uploader.proto import export_service_pb2_grpc
@@ -416,7 +417,7 @@ def execute(self, server_info, channel):
             verbosity=self.verbosity,
             one_shot=self.one_shot,
         )
-        if self.one_shot and not os.path.isdir(self.logdir):
+        if self.one_shot and not tf.io.gfile.isdir(self.logdir):
             print("%s: No such directory." % self.logdir)
             print(
                 "User specified `one_shot` mode with an unavailable "