returncode for Popen is valid only after communicate call

Found when testing a bug in cinder (1125416), code
relying on throw_on_error won't work because returncode
is None if checked before the communicate() method is
called

Change-Id: I8c9dd00396346ec3ad7bbe1dc17643c385da8d6f

1 files changed, 1 insertions, 1 deletions

diff --git a/setup.py b/setup.py
index 35680b3..2a971e7 100644
--- a/setup.py
+++ b/setup.py
@@ -117,9 +117,9 @@ def _run_shell_command(cmd, throw_on_error=False):
         output = subprocess.Popen(["/bin/sh", "-c", cmd],
                                   stdout=subprocess.PIPE,
                                   stderr=subprocess.PIPE)
+    out = output.communicate()
     if output.returncode and throw_on_error:
         raise Exception("%s returned %d" % cmd, output.returncode)
-    out = output.communicate()
     if len(out) == 0:
         return None
     if len(out[0].strip()) == 0: