We recently had a couple of team upgrade their Jenkins servers to the 1.580.1 LTS version (pushed 10/29 by the Jenkins people). Since they have upgraded, we have had strange behavior authenticating RTC and those machines. The setup has been working for some time using the prior Jenkins LTS version (1.565.x).

The behavior change is in the Authentication piece of the Build Engine definition in RTC.
If we check the "Authentication Required" box, Jenkins will return a 401 error even though the credentials work fine if you log into the Jenkins server directly.
Further, if we UN-check the box, the builds will run fine AND show that the credentials previously entered in the Build Engine definition (i.e. when the "Authentication Required" box was checked) were used to request the build in Jenkins.

We have tested it by:

1. changing the credentials in the Build Engine
2. trying a build with the 'Authentication Required' box checked (consistently getting an auth failure 401 error)
3. unchecking the box
4. re-requesting the same build (consistently getting successful build start in Jenkins)

The behavior is consistent in multiple project areas.
Our main RTC server is 4.0.7, but we were able to reproduce the behavior using our CLM5.0.1 test server.
Both Jenkins servers are on RedHat Linux and use our LDAP for authentication.

There appear to have been a number of security enhancements in Jenkins quite recently, so we are wondering if there is a lag in compatibility on the RTC side?

We have a workaround - albeit a pretty weak one - for now.
Has anyone else seen this?
Are there any hotfixes we need?