Description of problem:
I started two deployments in parallel. One for RHEV+CFME and the other for RHELOSP. Both of them are now syncing content, but the second one (RHELOSP) reports sub task failed. The sub task:

Id: a2cc12a5-ebe0-4584-8c8c-26c7982b91e4
Label: Actions::Katello::Repository::Sync
Name: Synchronize
Owner: admin
Started at: 2016-01-27 10:56:20 UTC
Ended at: 2016-01-27 10:56:22 UTC
State: stopped
Result: error
Params: repository 'Red Hat Enterprise Linux 7 Server Kickstart x86_64 7.1'; product 'Red Hat Enterprise Linux Server'; organization 'Default Organization'

reports error:

Required lock is already taken by other running tasks.
Please inspect their state, fix their errors and resume them.

Required lock: read
Conflicts with tasks:
- https://<URL>/foreman_tasks/tasks/48b8eefb-3174-4924-8ac2-9f56372ae0d2

The conflicting task is:

Id: 48b8eefb-3174-4924-8ac2-9f56372ae0d2
Label: Actions::Fusor::Content::ManageContent
Name: Manage Content
Owner: admin
Started at: 2016-01-27 10:37:02 UTC
Ended at:
State: running
Result: -
Params: {"services_checked"=> ["pulp", "pulp_auth", "candlepin", "candlepin_auth", "elasticsearch"], "locale"=>"en"} 

which is the manage content task for the first deployment (RHEVM+CFME).

Version-Release number of selected component (if applicable):
RHCI-6.0-RHEL-7-20160126.7-RHCI-x86_64-dvd1.iso
RHCIOOO-7-RHEL-7-20160126.2-RHCIOOO-x86_64-dvd1.iso

How reproducible:
Happened to me once

Steps to Reproduce:
1. Do two parallel deployments in such a way that they will try to sync content at the same time
2. Inspect Installation Progress screen of the second deployment
3.

Actual results:
Sub task failed; Required lock is already taken by other running tasks

Expected results:
Maybe the second task should wait for the first task to finish

Additional info: