Grating commit access to a plugin fails

[Vojtech Juranek]

Hi,
I was asked by jsvitak to grant him commit access to jbpm-workflow-plugin [1],
but when I tried to do so via IRC bot, it fails with

13:49] <vjuranek> jenkins-admin: Make jsvitak a committer of jbpm-workflow-
plugin
[13:49] <jenkins-admin> Failed to create a repository: {"message":"Server
Error"}

Any idea what's wrong or for a work around (I tried to add him manually, but I
don't see such option for this plugin on web UI)

Thanks
Vojta

[1] https://github.com/jenkinsci/jbpm-workflow-plugin