Make Pants goal run for Python exit with error code 1 if the python

program exits non-zero (as pants goal run does for java).

Testing Done:
Ran new tests.

Reviewed at https://rbcommons.com/s/twitter/r/1374/

src/python/pants/backend/python/tasks/python_run.py

@@ -48,9 +48,14 @@ def execute(self):
         pex = PEX(builder.path(), interpreter=interpreter)
         self.context.lock.release()
         with self.context.new_workunit(name='run', labels=[WorkUnit.RUN]):
-          po = pex.run(blocking=False, args=self.get_options().args + self.get_passthru_args())
+          args = self.get_options().args + self.get_passthru_args()
+          po = pex.run(blocking=False, args=args)
           try:
-            return po.wait()
+            result = po.wait()
+            if result != 0:
+              raise TaskError('python {args} ... exited non-zero ({code})' %
+                              dict(args=args, code=result),
+                              exit_code=result)
           except KeyboardInterrupt:
             po.send_signal(signal.SIGINT)
             raise

tests/python/pants_test/python/BUILD

@@ -155,3 +155,18 @@ python_binary(
   entry_point = 'pants_test.python.echo_interpreter_version',
   compatibility = ['CPython<2.6']
 )
+
+python_library(
+  name = 'die_lib',
+  sources = ['die.py'],
+  dependencies = [],
+  compatibility = ['CPython>=2.6,<3']
+)
+
+python_binary(
+  name = 'die',
+  dependencies = [
+    ':die_lib',
+  ],
+  entry_point = 'pants_test.python.die',
+)

tests/python/pants_test/python/die.py

@@ -0,0 +1,12 @@
+# coding=utf-8
+# Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+from __future__ import (nested_scopes, generators, division, absolute_import, with_statement,
+                        print_function, unicode_literals)
+
+import sys
+
+
+print('Exiting with status 1')
+sys.exit(1)

tests/python/pants_test/python/test_python_run_integration.py

@@ -18,6 +18,13 @@ def test_run_26(self):
   def test_run_27(self):
     self._maybe_run_version('2.7')
 
+  def test_die(self):
+    command = ['goal', 'run', 'tests/python/pants_test/python:die'
+               '--interpreter=CPython>=2.6,<3',
+               '--interpreter=CPython>=3.3', '--quiet']
+    pants_run = self.run_pants(command=command)
+    assert pants_run.returncode == 1
+
   def _maybe_run_version(self, version):
     if self.has_python_version(version):
       print('Found python %s. Testing running on it.' % version)