fix partitionNum calculation & remove extra sorting

pom.xml

@@ -41,7 +41,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <metamx.java-util.version>0.26.5</metamx.java-util.version>
         <apache.curator.version>2.5.0</apache.curator.version>
-        <druid.api.version>0.2.5</druid.api.version>
+        <druid.api.version>0.2.5-SNAPSHOT</druid.api.version>
     </properties>
 
     <modules>

server/src/main/java/io/druid/timeline/partition/HashBasedNumberedShardSpec.java

@@ -30,8 +30,6 @@ import com.google.common.hash.Hashing;
 import io.druid.data.input.InputRow;
 import io.druid.data.input.Rows;
 
-import java.util.Collections;
-import java.util.Comparator;
 import java.util.List;
 
 public class HashBasedNumberedShardSpec extends NumberedShardSpec
@@ -79,24 +77,12 @@ public class HashBasedNumberedShardSpec extends NumberedShardSpec
   @Override
   public ShardSpecLookup getLookup(final List<ShardSpec> shardSpecs)
   {
-    // Sort on basis of partitionNumber
-    Collections.sort(
-        shardSpecs, new Comparator<ShardSpec>()
-    {
-      @Override
-      public int compare(ShardSpec o1, ShardSpec o2)
-      {
-        return Integer.compare(o1.getPartitionNum(), o2.getPartitionNum());
-      }
-    }
-    );
-
     return new ShardSpecLookup()
     {
       @Override
       public ShardSpec getShardSpec(InputRow row)
       {
-        int index = (int) ((long) hash(row)) % getPartitions();
+        int index = Math.abs(hash(row) % getPartitions());
         return shardSpecs.get(index);
       }
     };

server/src/test/java/io/druid/server/shard/HashBasedNumberedShardSpecTest.java

@@ -194,4 +194,16 @@ public class HashBasedNumberedShardSpecTest
       return 0;
     }
   }
+
+  @Test
+  public void testValidity(){
+    for(int i=Integer.MIN_VALUE;i<=Integer.MAX_VALUE;i++){
+      {
+        int partitionNum = Math.abs((int) ((long) i % 2));
+        if(partitionNum != 0 && partitionNum != 1){
+          throw new ISE("for i "+ i+ "partitionNum "+ partitionNum);
+        }
+      }
+  }
+  }
 }