PluginManager: Fix config path extraction from plugin handle

The PluginManager had a subtle bug in case the config directory was not in the
es home directory - which is always true in case of packaging.

This fixes the plugin manager, so that when specifying a path.home and a
path.conf variable on the commandline, the plugin manager acts
appropriately.

src/main/java/org/elasticsearch/plugins/PluginManager.java

@@ -654,7 +654,7 @@ public class PluginManager {
         }
 
         File configDir(Environment env) {
-            return new File(new File(env.homeFile(), "config"), name);
+            return new File(env.configFile(), name);
         }
 
         static PluginHandle parse(String name) {

src/test/java/org/elasticsearch/plugins/PluginManagerUnitTests.java

@@ -0,0 +1,57 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.plugins;
+
+import com.google.common.io.Files;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.env.Environment;
+import org.elasticsearch.test.ElasticsearchTestCase;
+import org.junit.Test;
+
+import java.io.File;
+
+import static org.elasticsearch.common.settings.ImmutableSettings.settingsBuilder;
+import static org.hamcrest.Matchers.is;
+
+/**
+ *
+ */
+public class PluginManagerUnitTests extends ElasticsearchTestCase {
+
+    @Test
+    public void testThatConfigDirectoryCanBeOutsideOfElasticsearchHomeDirectory() {
+        String pluginName = randomAsciiOfLength(10);
+        File homeFolder = newTempDir();
+        File genericConfigFolder = newTempDir();
+
+        Settings settings = settingsBuilder()
+                .put("path.conf", genericConfigFolder)
+                .put("path.home", homeFolder)
+                .build();
+        Environment environment = new Environment(settings);
+
+        PluginManager.PluginHandle pluginHandle = new PluginManager.PluginHandle(pluginName, "version", "user", "repo");
+
+        String configDirPath = Files.simplifyPath(pluginHandle.configDir(environment).getAbsolutePath());
+        String expectedDirPath = Files.simplifyPath(new File(genericConfigFolder, pluginName).getAbsolutePath());
+
+        assertThat(configDirPath, is(expectedDirPath));
+    }
+}