Description of problem:
when perform stop-metrics-0.1 again, it will prompt "Node execution failure
(invalid exit code from node)."

Version-Release number of selected component (if applicable):
rhc-0.85.10-1.el6_2.noarch

How reproducible:
always

Steps to Reproduce:
1. create an app
# rhc-create-app -a perltest -l bzhao -p redhat -t perl-5.10

2. embed metrics-0.1 cartridge
# rhc-ctl-app -a perltest -l bzhao -p redhat -e add-metrics-0.1

3. stop this metrics using rhc-ctl-app
# rhc-ctl-app -a perltest -l bzhao -p redhat -e stop-metrics-0.1

4. stop this metrics again
# rhc-ctl-app -a perltest -l bzhao -p redhat -e stop-metrics-0.1
  
Actual results:
output "Node execution failure (invalid exit code from node)."

Expected results:
it should return rockmongo has stopped or others info, such as: result success

Additional info:
# rhc-ctl-app -a perltest -predhat -e stop-metrics-0.1 -d
Contacting https://ec2-50-19-130-191.compute-1.amazonaws.com
Problem reported from server. Response code was 500.

DEBUG:
Cartridge return code: 1

Exit Code: 1
broker_c: namespacerhloginsshapp_uuiddebugaltercartridgecart_typeactionapp_nameapi
api_c: placeholder
API version:    1.1.2
Broker version: 1.1.1

RESULT:
Node execution failure (invalid exit code from node).  If the problem persists please contact Red Hat support.