Index: src/main/java/hudson/model/AbstractBuild.java
===================================================================
--- src/main/java/hudson/model/AbstractBuild.java	(revision 36016)
+++ src/main/java/hudson/model/AbstractBuild.java	(working copy)
@@ -1077,6 +1077,11 @@
             // nothing is building
             rsp.forwardToPreviousPage(req);
     }
+    
+    @Override
+    protected Computer getComputer() {
+        return getBuiltOn().toComputer();
+    }
 
     private static final Logger LOGGER = Logger.getLogger(AbstractBuild.class.getName());
 }
Index: src/main/java/hudson/model/Run.java
===================================================================
--- src/main/java/hudson/model/Run.java	(revision 36016)
+++ src/main/java/hudson/model/Run.java	(working copy)
@@ -1116,6 +1116,14 @@
 
         removeRunFromParent();
     }
+    
+    /**
+     * Get the computer this run is running on. Subclasses can override this
+     * @return 
+     */
+    protected Computer getComputer() {
+        return Computer.currentComputer();
+    }
 
     @SuppressWarnings("unchecked") // seems this is too clever for Java's type system?
     private void removeRunFromParent() {
@@ -1677,7 +1685,7 @@
      * @since 1.305
      */
     public EnvVars getEnvironment(TaskListener log) throws IOException, InterruptedException {
-        EnvVars env = Computer.currentComputer().getEnvironment().overrideAll(getCharacteristicEnvVars());
+        EnvVars env = getComputer().getEnvironment().overrideAll(getCharacteristicEnvVars());
         String rootUrl = Hudson.getInstance().getRootUrl();
         if(rootUrl!=null) {
             env.put("HUDSON_URL", rootUrl);