Fix `device.PushChangedFiles(delete_device_stale=True)` when no device files currently exist

build/android/pylib/device/device_utils.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Provides a variety of device interactions based on adb.
 
 Eventually, this will be based on adb_wrapper.
 """
 # pylint: disable=unused-argument
 
@@ skipping 995 matching lines @@
     all_changed_files = []
     all_stale_files = []
     for h, d in host_device_tuples:
       if os.path.isdir(h):
         self.RunShellCommand(['mkdir', '-p', d], check_return=True)
       changed_files, stale_files = (
           self._GetChangedAndStaleFiles(h, d, delete_device_stale))
       all_changed_files += changed_files
       all_stale_files += stale_files
 
-    if delete_device_stale:
+    if delete_device_stale and all_stale_files:
       self.RunShellCommand(['rm', '-f'] + all_stale_files,
                              check_return=True)
 
-    if not all_changed_files:
-      return
-
-    self._PushFilesImpl(host_device_tuples, all_changed_files)
+    if all_changed_files:
+      self._PushFilesImpl(host_device_tuples, all_changed_files)
 
   def _GetChangedAndStaleFiles(self, host_path, device_path, track_stale=False):
     """Get files to push and delete
 
     Args:
       host_path: an absolute path of a file or directory on the host
       device_path: an absolute path of a file or directory on the device
       track_stale: whether to bother looking for stale files (slower)
 
     Returns:
@@ skipping 848 matching lines @@
     return [cls(adb) for adb in adb_wrapper.AdbWrapper.Devices()
             if not blacklisted(adb)]
 
   @decorators.WithTimeoutAndRetriesFromInstance()
   def RestartAdbd(self, timeout=None, retries=None):
     logging.info('Restarting adbd on device.')
     with device_temp_file.DeviceTempFile(self.adb, suffix='.sh') as script:
       self.WriteFile(script.name, _RESTART_ADBD_SCRIPT)
       self.RunShellCommand(['source', script.name], as_root=True)
       self.adb.WaitForDevice()