Description of problem:
Given a scaling app with a disable_auto_scaling marker added, the app will automatically scale down after scaling up via REST API. Currently, the following cartridges are covered:

python-2.7
python-3.3

will append the list in comments if find others.

Version-Release number of selected component (if applicable):
devenv_3880

How reproducible:
always

Steps to Reproduce:
1. create a scaling app
2. create a disable_auto_scaling marker
3. push the marker to its remote repo
4. scale up the app via REST API
5. check the scaled-up gear and the haproxy-status page
6. wait for sometime (in my test, it was around 10 mins)
7. repeat step 5
8. check the scale_events.log
9. check if the disable_auto_scaling marker is at presence

Actual results:
In Step 5, the app was scaled up successfully, and the scaled-up gear was accessible. However, in Step 7, only the local gear was shown in the haproxy-status page, and it returned error 503 when accessing the scaled-up gear. Moreover, in the scale_events.log, the sscaled-up gear was scaled-down:

I, [2013-10-10T04:36:54.139800 #14505]  INFO -- : GEAR_DOWN - capacity: 0.0% gear_count: 2 sessions: 0 remove_thresh: 40.5%

but the disable_auto_scaling marker was in the app's repo

Expected results:
The scaled app should not be scaled down with the disable_auto_scaling marker at presence.

Additional info: