When setting a new default view in a folder, already existing config files get deleted

Steps to reproduce:

1. create a folder
2. create a config file 'some config'
3. create job 'test1'
4. create job 'test2'
5. create a new view 'test2 only' and assign job test2
6. edit the folder and set 'test2 only' as default view

Expected result:

default view is changed, all configuration files still exist in all views

Actual result:

default view changed, all configuration files deleted

Also switching back the default view does not recover the deleted configuration files

There is a issue, which should be fixed in 2.15.7 by Dominik Bartholdi:

https://issues.jenkins-ci.org/browse/JENKINS-42389