[utils] Handle JSON decode error in ckan_post

.json() may fail, see http://docs.python-requests.org/en/latest/user/quickstart/#json-response-content.

utils.py

@@ -34,11 +34,17 @@ def ckan_post(config, action, data=None):
     url = urljoin(base, 'api/3/action/' + action)
     headers = {'Authorization': config['ckan-api-key'],
                'Content-Type': 'application/json'}
-    r = requests.post(url, headers=headers, data=json.dumps(data or {}))
-    if not r.ok:
-        error = r.json()['error']
+    resp = requests.post(url, headers=headers, data=json.dumps(data or {}))
+    try:
+        jresp = resp.json()
+    except ValueError:
+        error = resp.text
+    else:
+        if resp.ok:
+            return jresp['result']
+        else:
+            error = jresp['error']
     raise CKANPostError('action %s failed: %s' % (action, error))
-    return r.json()['result']
 
 
 @objectify_predicate