[RHV] engine does not answer correctly to paged requests

Issue

• cluster needs to be scrutinized by ILMT (IBM License Metric Tool)
  Basically, what ILMT does is this:

GET /ovirt-engine/api/vms?search=page%201
GET /ovirt-engine/api/vms?search=page%202
GET /ovirt-engine/api/vms?search=page%203

until it gets an empty XML response. Then it does

GET /ovirt-engine/api/hosts?search=page%201
GET /ovirt-engine/api/hosts?search=page%202
GET /ovirt-engine/api/hosts?search=page%203

again until it gets an empty XML response.
Unfortunately, that empty response never comes because we only have 12 hosts and RHV repeats answering with the first page over and over.
We stopped that process at page 65,000 last time …

What you see in /var/log/httpd/ovirt-requests-log (condensed):

 1 GET /ovirt-engine/api 4680
 2 GET /ovirt-engine/api/vms?search=page%201 2860849
 3 GET /ovirt-engine/api/vms?search=page%202 63
 4 GET /ovirt-engine/api/hosts?search=page%201 96092
 5 GET /ovirt-engine/api/hosts?search=page%202 96092
 6 GET /ovirt-engine/api/hosts?search=page%203 96092
 7 GET /ovirt-engine/api/hosts?search=page%204 96092
 8 GET /ovirt-engine/api/hosts?search=page%205 96092
 9 GET /ovirt-engine/api/hosts?search=page%206 96092
10 GET /ovirt-engine/api/hosts?search=page%207 96092
11 GET /ovirt-engine/api/hosts?search=page%208 96092
12 GET /ovirt-engine/api/hosts?search=page%209 96092
13 GET /ovirt-engine/api/hosts?search=page%2010 96092
14 GET /ovirt-engine/api/hosts?search=page%2011 96092

The last number in each line is the response length in bytes.

The answer to line 3 looks like this:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<vms/>

We would expect something like this in line 5.
Instead, we get the same answer as we get in line 4 (our 12 hosts).
You can see that the response length is - unexpectedly - always the same.