this is with Jenkins ver. 1.424.1
this is with Jenkins GIT plugin version 1.1.14 -- I was unable to enter the version number in the 'Affects Version(s)' box.
When Matrix Authorization Strategy is used, and Anonymous does not have Job Read access (which is the default), "No git jobs found" is returned when the .../git/notifyCommit?url=... URL is requested.
(No per-job auth schemes were created yet in our set up)
I would not be surprised when other Authorization Strategies are limiting in a similar way.
I wonder whether the same issue applies to other SCM's – I think I read that for SVN there is a similar push notification mechanism.