[FIXED HUDSON-6429] Check for null results to handle aborted incremental Maven...

[FIXED HUDSON-6429] Check for null results to handle aborted incremental Maven builds - thanks to kutzi for the patch

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@33250 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/Run.java

@@ -654,7 +654,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      */
     public RunT getPreviousBuiltBuild() {
         RunT r=previousBuild;
-        while( r!=null && r.getResult()==Result.NOT_BUILT )
+        // in certain situations (aborted m2 builds) r.getResult() can still be null, although it should theoretically never happen
+        while( r!=null && (r.getResult() == null || r.getResult()==Result.NOT_BUILT) )
             r=r.previousBuild;
         return r;
     }