Returncode is null on destination when value is 0 (zero)

[Juanma-Segura]

At the moment of recieving the XML dictionary on destination with tag status this tag is empty when its value is zero.

This is an example of void tag status parsed to JSON:

{
	"@type": "service",
	"servicename": "CPU Usage",
	"hostname": "my.servername.local",
	"state": null,
	"output": "OK: Percent was 2.82 % | percent=2.82%;60;80;"
}

And this is the original message:

<QueryDict: {'token': ['SUPERSECRETTOKEN'], 'XMLDATA': ['<?xml version="1.0" ?><checkresults><checkresult type="service"><servicename>CPU Usage</servicename><hostname>my.servername.local</hostname><state/><output>OK: Percent was 2.01 % | \'percent\'=2.01%;60;80;</output></checkresult></checkresults>'], 'cmd': ['submitcheck']}>

Taking a look at the code, the value "is lost" at the moment of converting the dictionary into a xml. I would like to know if it is the desired behaviour or if it's an uncontrolled side effect.

In the second case, the problem could be solved just adding strict conversion to string at line 69 of the file agent/passive/nrpd.py. Of course I'll be glad to make the PR for this if you would like to.

Many thanks in advance.