Nullpointer in AbstractRepositoryManager#handleRemoteIndexFile

I found that in some rare cases the handleRemoteIndexFile could run into
a NPE if the Transport service can't be fetched.

This now checks first for null before using the transport and if it is
null fall back to simple URL stream, if that also fails, create an empty
index file.

bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/internal/p2/repository/helpers/AbstractRepositoryManager.java

@@ -739,12 +739,21 @@ private LocationProperties loadIndexFile(URI location, IProgressMonitor monitor)
 	private LocationProperties handleRemoteIndexFile(URI indexFileURI, IProgressMonitor monitor) {
 		ByteArrayOutputStream index = new ByteArrayOutputStream();
 		IStatus indexFileStatus = null;
-		indexFileStatus = getTransport().download(indexFileURI, index, monitor);
-		while (indexFileStatus.getCode() == IArtifactRepository.CODE_RETRY) {
-			indexFileStatus = getTransport().download(indexFileURI, index, monitor);
+		Transport transport = getTransport();
+		if (transport != null) {
+			indexFileStatus = transport.download(indexFileURI, index, monitor);
+			while (indexFileStatus.getCode() == IArtifactRepository.CODE_RETRY) {
+				indexFileStatus = transport.download(indexFileURI, index, monitor);
+			}
+			if (indexFileStatus != null && indexFileStatus.isOK())
+				return LocationProperties.create(new ByteArrayInputStream(index.toByteArray()));
+		} else {
+			try (InputStream openStream = indexFileURI.toURL().openStream()) {
+				return LocationProperties.create(openStream);
+			} catch (IOException e) {
+				// nothing more to do here...
+			}
 		}
-		if (indexFileStatus != null && indexFileStatus.isOK())
-			return LocationProperties.create(new ByteArrayInputStream(index.toByteArray()));
 		return LocationProperties.createEmptyIndexFile();
 	}