Fix possible NPEs when reporting transport errors

There was a bug in JGit which caused NPEs being thrown when Transport
errors should be reported. Avoid the NPE to let the original error show
up.

Change-Id: I9e1e2b0195bd61b7e531a09d0fc7bce109bd6515

org.eclipse.jgit/src/org/eclipse/jgit/util/HttpSupport.java

@@ -189,7 +189,8 @@ public class HttpSupport {
 		try {
 			return c.getResponseCode();
 		} catch (ConnectException ce) {
-			final String host = c.getURL().getHost();
+			final URL url = c.getURL();
+			final String host = (url == null) ? "<null>" : url.getHost();
 			// The standard J2SE error message is not very useful.
 			//
 			if ("Connection timed out: connect".equals(ce.getMessage())) //$NON-NLS-1$
@@ -216,7 +217,8 @@ public class HttpSupport {
 		try {
 			return c.getResponseCode();
 		} catch (ConnectException ce) {
-			final String host = c.getURL().getHost();
+			final URL url = c.getURL();
+			final String host = (url == null) ? "<null>" : url.getHost();
 			// The standard J2SE error message is not very useful.
 			//
 			if ("Connection timed out: connect".equals(ce.getMessage())) //$NON-NLS-1$