Merge pull request #323 from carlossg/invalid-http

Handle invalid HTTP received from server

core/src/main/java/feign/Client.java

@@ -15,6 +15,8 @@
  */
 package feign;
 
+import static java.lang.String.format;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -150,6 +152,12 @@ public interface Client {
       int status = connection.getResponseCode();
       String reason = connection.getResponseMessage();
 
+      if (status < 0 || reason == null) {
+        // invalid response
+        throw new IOException(format("Invalid HTTP executing %s %s", connection.getRequestMethod(),
+            connection.getURL()));
+      }
+
       Map<String, Collection<String>> headers = new LinkedHashMap<String, Collection<String>>();
       for (Map.Entry<String, List<String>> field : connection.getHeaderFields().entrySet()) {
         // response message