[JENKINS-27178] Amended merge of #1590.

(cherry picked from commit 87ab95e7)

changelog.html

@@ -63,6 +63,9 @@ Upcoming changes</a>
 <div id="rc" style="display:none;"><!--=BEGIN=-->
 <h3><a name=v1.601>What's new in 1.601</a> <!--=DATE=--></h3>
 <ul class=image>
+  <li class="major bug">
+    Regression with environment variables in 1.600.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-27188">issue 27188</a>)
   <li class=bug>
     Errors in Dashboard View plugin since 1.597.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-26690">issue 26690</a>)

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

@@ -942,18 +942,18 @@ public /*transient*/ abstract class Computer extends Actionable implements Acces
     }
 
     /**
-     * Gets the environment variables of the JVM on this computer.
+     * Returns cached environment variables (copy to prevent modification) for the JVM on this computer.
      * If this is the master, it returns the system property of the master computer.
      */
     public EnvVars getEnvironment() throws IOException, InterruptedException {
         EnvVars cachedEnvironment = this.cachedEnvironment;
         if (cachedEnvironment != null) {
-            return cachedEnvironment;
+            return new EnvVars(cachedEnvironment);
         }
 
         cachedEnvironment = EnvVars.getRemote(getChannel());
         this.cachedEnvironment = cachedEnvironment;
-        return cachedEnvironment;
+        return new EnvVars(cachedEnvironment);
     }
 
     /**

test/src/test/java/hudson/model/NodeTest.java

@@ -23,6 +23,7 @@
  */
 package hudson.model;
 
+import hudson.EnvVars;
 import hudson.FilePath;
 import hudson.model.Node.Mode;
 import hudson.model.Queue.WaitingItem;
@@ -52,6 +53,7 @@ import static org.junit.Assert.*;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
+import org.jvnet.hudson.test.Issue;
 import org.jvnet.hudson.test.JenkinsRule;
 import org.jvnet.hudson.test.MockQueueItemAuthenticator;
 import org.jvnet.hudson.test.TestExtension;
@@ -238,6 +240,19 @@ public class NodeTest {
         assertNotNull("Slave which is added into Jenkins list nodes should have assigned computer.", slave.toComputer());
     }
     
+    @Issue("JENKINS-27188")
+    @Test public void envPropertiesImmutable() throws Exception {
+        Slave slave = j.createSlave();
+
+        String propertyKey = "JENKINS-27188";
+        EnvVars envVars = slave.getComputer().getEnvironment();
+        envVars.put(propertyKey, "huuhaa");
+        assertTrue(envVars.containsKey(propertyKey));
+        assertFalse(slave.getComputer().getEnvironment().containsKey(propertyKey));
+
+        assertNotSame(slave.getComputer().getEnvironment(), slave.getComputer().getEnvironment());
+    }
+
     @TestExtension
     public static class LabelFinderImpl extends LabelFinder{