USE subprocess.Popen API correctly.

When collecting stdout/stderr *and* feeding data into a Popen instance,
communicate() must be used to avoid a known deadlocking scenario
when data sizes cross PIPE_BUF (which can be as small as 512, although should
be much larger in practice on linux).

lib/ansible/module_common.py

@@ -935,10 +935,9 @@ class AnsibleModule(object):
                                    stdout=subprocess.PIPE,
                                    stderr=subprocess.PIPE)
             if data:
-                cmd.stdin.write(data)
                 if not binary_data:
-                    cmd.stdin.write('\\n')
+                    data += '\\n'
-            out, err = cmd.communicate()
+            out, err = cmd.communicate(input=data)
             rc = cmd.returncode
         except (OSError, IOError), e:
             self.fail_json(rc=e.errno, msg=str(e), cmd=args)