chore(builder): show docker push output from builder for debugging

Author: Gabriel Monroy

builder/templates/builder

@@ -95,8 +95,8 @@ if __name__ == '__main__':
         # push the image, output to /dev/null
         print('-----> Pushing image to private registry')
         sys.stdout.flush(), sys.stderr.flush()
-        p = subprocess.Popen('docker push {target_image}'.format(**locals()), shell=True,
-                             stdout=open(os.devnull, 'w'), stderr=open(os.devnull, 'w'))
+        p = subprocess.Popen('docker push {target_image}'.format(**locals()), shell=True)
+        #                     stdout=open(os.devnull, 'w'), stderr=open(os.devnull, 'w'))
         rc = p.wait()
         if rc != 0:
             raise Exception('Could not push Docker image')