Merge branch 'master' into whitelist-JENKINS-47736

core/src/main/java/hudson/PluginManager.java

@@ -120,7 +120,6 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
-import java.util.ListIterator;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
@@ -144,6 +143,7 @@ import hudson.util.FormValidation;
 import java.io.ByteArrayInputStream;
 import java.net.JarURLConnection;
 import java.net.URLConnection;
+import java.util.ServiceLoader;
 import java.util.jar.JarEntry;
 
 import static java.util.logging.Level.FINE;
@@ -651,7 +651,17 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
                     continue;
                 }
 
-                String artifactId = dependencyToken.split(":")[0];
+                String[] artifactIdVersionPair = dependencyToken.split(":");
+                String artifactId = artifactIdVersionPair[0];
+                VersionNumber dependencyVersion = new VersionNumber(artifactIdVersionPair[1]);
+
+                PluginManager manager = Jenkins.getActiveInstance().getPluginManager();
+                VersionNumber installedVersion = manager.getPluginVersion(manager.rootDir, artifactId);
+                if (installedVersion != null && !installedVersion.isOlderThan(dependencyVersion)) {
+                    // Do not downgrade dependencies that are already installed.
+                    continue;
+                }
+
                 URL dependencyURL = context.getResource(fromPath + "/" + artifactId + ".hpi");
 
                 if (dependencyURL == null) {
@@ -680,9 +690,8 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
      * </ul>
      */
     protected void loadDetachedPlugins() {
-        InstallState installState = Jenkins.getActiveInstance().getInstallState();
-        if (InstallState.UPGRADE.equals(installState)) {
-            VersionNumber lastExecVersion = new VersionNumber(InstallUtil.getLastExecVersion());
+        VersionNumber lastExecVersion = new VersionNumber(InstallUtil.getLastExecVersion());
+        if (lastExecVersion.isNewerThan(InstallUtil.NEW_INSTALL_VERSION) && lastExecVersion.isOlderThan(Jenkins.getVersion())) {
 
             LOGGER.log(INFO, "Upgrading Jenkins. The last running version was {0}. This Jenkins is version {1}.",
                     new Object[] {lastExecVersion, Jenkins.VERSION});
@@ -1199,7 +1208,9 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
     /**
      * Discover all the service provider implementations of the given class,
      * via <tt>META-INF/services</tt>.
+     * @deprecated Use {@link ServiceLoader} instead, or (more commonly) {@link ExtensionList}.
      */
+    @Deprecated
     public <T> Collection<Class<? extends T>> discover( Class<T> spi ) {
         Set<Class<? extends T>> result = new HashSet<Class<? extends T>>();