Fix hanging test suite when dosep.py is invoked directly.

[chaoren]

I remember we ran into this same problem when I first wrote the timeout code. which is why the stdin=subprocess.PIPE was originally there.

[zturner]

lgtm if you say this fixes it. But do you know why the stdin=subprocess.PIPE necessary? The subprocess should never even receive any stdin should it?

test/dosep.py

 def call_with_timeout(command, timeout):
     """Run command with a timeout if possible."""
     """-s QUIT will create a coredump if they are enabled on your system"""
     process = None
     if timeout_command and timeout != "0":
         command = [timeout_command, '-s', 'QUIT', timeout] + command
     # Specifying a value for close_fds is unsupported on Windows when using subprocess.PIPE
     if os.name != "nt":
-        process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=True)
+        process = subprocess.Popen(command, stdin=subprocess.PIPE,
+                                            stdout=subprocess.PIPE,
+                                            stderr=subprocess.PIPE,
+                                            close_fds=True)
     else:
-        process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        process = subprocess.Popen(command, stdin=subprocess.PIPE,
+                                            stdout=subprocess.PIPE,
+                                            stderr=subprocess.PIPE)
     output = process.communicate()
     exit_status = process.returncode
     passes, failures = parse_test_results(output)
     return exit_status, passes, failures
 
 def process_dir(root, files, test_root, dotest_argv):
     """Examine a directory for tests, and invoke any found within it."""
     timed_out = []