install needed maven installation for testing in ${project.build.directory}

so not delete/unzip anymore for all units but reuse already extracted one.
preserve io stuff :-)

test/pom.xml

@@ -78,7 +78,11 @@ THE SOFTWARE.
                 <property>
                   <name>java.io.tmpdir</name>
                   <value>${project.build.directory}</value>
-                </property>                
+                </property> 
+                <property>
+                  <name>buildDirectory</name>
+                  <value>${project.build.directory}</value>
+                </property>                               
               </systemProperties>
             </configuration>
           </execution>

test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java

@@ -406,6 +406,15 @@ public abstract class HudsonTestCase extends TestCase implements RootAction {
      */
     protected MavenInstallation configureDefaultMaven(String mavenVersion, int mavenReqVersion) throws Exception {
         // first if we are running inside Maven, pick that Maven, if it meets the criteria we require..
+        // does it exists in the buildDirectory see maven-junit-plugin systemProperties 
+        // buildDirectory -> ${project.build.directory} (so no reason to be null ;-) )
+        String buildDirectory = System.getProperty( "buildDirectory" );
+        File mavenAlreadyInstalled = new File(buildDirectory, mavenVersion);
+        if (mavenAlreadyInstalled.exists()) {
+            MavenInstallation mavenInstallation = new MavenInstallation("default",mavenAlreadyInstalled.getAbsolutePath(), NO_PROPERTIES);
+            hudson.getDescriptorByType(Maven.DescriptorImpl.class).setInstallations(mavenInstallation);
+            return mavenInstallation;
+        }
         String home = System.getProperty("maven.home");
         if(home!=null) {
             MavenInstallation mavenInstallation = new MavenInstallation("default",home, NO_PROPERTIES);
@@ -421,7 +430,7 @@ public abstract class HudsonTestCase extends TestCase implements RootAction {
                 "To avoid a performance hit, set the system property 'maven.home' to point to a Maven2 installation.");
         FilePath mvn = hudson.getRootPath().createTempFile("maven", "zip");
         mvn.copyFrom(HudsonTestCase.class.getClassLoader().getResource(mavenVersion + "-bin.zip"));
-        File mvnHome = createTmpDir();
+        File mvnHome =  new File(buildDirectory);//createTmpDir();
         mvn.unzip(new FilePath(mvnHome));
         // TODO: switch to tar that preserves file permissions more easily
         if(!Functions.isWindows())