It appears that your build is defined with a narrow refspec ("refs/heads/develop"), but your build then assumes that the entire repository was fetched, even though a narrow refspec was provided. I believe that means your build depends on bug
JENKINS-31393 in the git plugin.
JENKINS-31393 was fixed in git plugin 2.5.1. Prior to git plugin 2.5.1, the refspec provided by the user was ignored for the initial fetch. That meant that no matter what refspec was provided by the user, the entire repository was fetched. Users with large repositories didn't like that the refspec they constructed was ignored on initial fetch, since it increased the size of the cloned repository and took longer to clone that repository.
With the fix of
JENKINS-31393, the refspec is honored on the initial fetch. One alternative to handle that case is to add an additional refspec to your job definition which will include all the commits. For example, your current refspec seems to be "refs/heads/develop". The new refspec could be
I'm not sure how your build could have been working for months with git plugin 2.5.0, since git plugin 2.5.0 released less than a month ago, 19 Jun 2016. Were you using one of the 2.5.0 beta versions prior to 19 Jun 2016, or was it that you were using git plugin 2.4.4 successfully for months?
There is a note in the changelog under 2.5.1 describing the risk of this happening. It says "some users may depend on the old, poor behavior that the plugin fetched all refspecs even though the user had specified a narrower refspec. Those users can delete their refspec or modify it to be as wide as they need". Unfortunately, I didn't see a way to preserve the old behavior (fetch everything) and fix
Another way to retain compatibility with the old "fetch everything initially" behavior would be to require that users who want the fix for
JENKINS-31393 must add the "Additional Behaviour" for "Advanced clone behaviours". In that "advanced behaviors" there would be a check box added to "Honor refspec on initial clone". If a large number of users are affected by this same condition, that may be the preferred approach.