Arbitrary ClassCastExceptions when using git-plugin (ChangeSet)

[Phleb4s]

I am using the hudson.plugins.cloneworkspace.CloneWorkspaceSCM plugin and my builds often fail due to a ClassCastException:

java.lang.ClassCastException: hudson.plugins.cloneworkspace.CloneWorkspaceSCM cannot be cast to hudson.plugins.git.GitSCM
    at     hudson.plugins.git.GitChangeSet.isCreateAccountBaseOnCommitterEmail(GitChangeSet.java:296)

The following patch would fix that issue:

-    if (parent != null) {
+        if (parent != null && GitSCM.class.isAssignableFrom(parent.getBuild().getProject().getScm().getClass())) {
         createAccountBaseOnCommitterEmail = ((GitSCM) parent.getBuild().getProject().getScm()).
             isCreateAccountBaseOnCommitterEmail();
        }

[bobfoster]

I guess the question is, why is the code trying to cast one SCM to another?

[wjprakash]

Hudson by default supports only one SCM. But using plugin you could have multiple SCM. I'm not sure if that is the issue.

[Phleb4s]

Of course that is the main question, why is Hudson trying to generate a changeset from the Git Plugin in the first place when the Job itself does use another SCM, e.g: CloneWorkspace. Maybe because the cloned workspace does look like a git repo, that is just my suggestion.
The strangest thing to me is that the error does only occur sometimes/most of the time but NOT always.

I have no experience in developing Hudson plugins however, so the suggested fix would simply prevent failing builds without going too deep into the cause.

[wjprakash]

I see. This fix seems good to me. Finding exactly why change-set generation is called on Git rather than configured SCM would be even better.