Make sure StreamWagon's are closed properly

Change-Id: I621068c307c8163b4e3007194e5b48c7c34b24d2
diff --git a/org.eclipse.tea.library.build/src/org/eclipse/tea/library/build/tasks/maven/SynchronizeMavenArtifact.java b/org.eclipse.tea.library.build/src/org/eclipse/tea/library/build/tasks/maven/SynchronizeMavenArtifact.java
index 225870a..5650c67 100644
--- a/org.eclipse.tea.library.build/src/org/eclipse/tea/library/build/tasks/maven/SynchronizeMavenArtifact.java
+++ b/org.eclipse.tea.library.build/src/org/eclipse/tea/library/build/tasks/maven/SynchronizeMavenArtifact.java
@@ -25,6 +25,8 @@
 import java.util.regex.Matcher;
 
 import org.apache.maven.repository.internal.MavenRepositorySystemUtils;
+import org.apache.maven.wagon.ConnectionException;
+import org.apache.maven.wagon.StreamWagon;
 import org.apache.maven.wagon.Wagon;
 import org.apache.maven.wagon.providers.file.FileWagon;
 import org.eclipse.aether.DefaultRepositorySystemSession;
@@ -344,6 +346,13 @@
 
 		@Override
 		public void release(Wagon wagon) {
+			if (wagon instanceof StreamWagon) {
+				try {
+					((StreamWagon) wagon).closeConnection();
+				} catch (ConnectionException e) {
+					throw new RuntimeException("Cannot close connection", e);
+				}
+			}
 		}
 
 	}