Remove remaining unused imports in webkitpy.

third_party/WebKit/Tools/Scripts/webkitpy/common/system/executive_unittest.py

 # Copyright (C) 2010 Google Inc. All rights reserved.
 # Copyright (C) 2009 Daniel Bates (dbates@intudata.com). All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #    * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #    * Redistributions in binary form must reproduce the above
@@ skipping 10 matching lines @@
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 import os
-import errno
-import signal
 import subprocess
 import sys
 import unittest
 
 # Since we execute this script directly as part of the unit tests, we need to ensure
 # that Tools/Scripts is in sys.path for the next imports to work correctly.
 script_dir = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
 if script_dir not in sys.path:
     sys.path.append(script_dir)
 
-
 from webkitpy.common.system.executive import Executive, ScriptError
 from webkitpy.common.system.filesystem_mock import MockFileSystem
 
 
 class ScriptErrorTest(unittest.TestCase):
 
     def test_message_with_output(self):
         error = ScriptError('My custom message!', '', -1)
         self.assertEqual(error.message_with_output(), 'My custom message!')
         error = ScriptError('My custom message!', '', -1, 'My output.')
@@ skipping 164 matching lines @@
         import msvcrt
         msvcrt.setmode(stdout.fileno(), os.O_BINARY)
     if cmd == '--cat':
         stdout.write(stdin.read())
     elif cmd == '--echo':
         stdout.write(' '.join(args))
     return 0
 
 if __name__ == '__main__' and len(sys.argv) > 1 and sys.argv[1] in ('--cat', '--echo'):
     sys.exit(main(sys.platform, sys.stdin, sys.stdout, sys.argv[1], sys.argv[2:]))