Do not use .netrc implicitly if no CredentialsProvider was set

Do not silently set the NetRCCredentialsProvider if no
CredentialsProvider was set explicitly since applications may want to
have full control which provider should be used.

Bug: 444338
Change-Id: Ie096983bc1caa90443a504d302bfea8f2d26ab9e
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportHttp.java

@@ -264,9 +264,6 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 		}
 		http = local.getConfig().get(HTTP_KEY);
 		proxySelector = ProxySelector.getDefault();
-
-		if (getCredentialsProvider() == null)
-			setCredentialsProvider(new NetRCCredentialsProvider());
 	}
 
 	/**