dfs: Fix incorrect use of reference == for DfsStreamKey

Must use .equals() now with DfsStreamKey.

Change-Id: I35fecbe3895c2078d69213e9c708a9b0613a1c7c
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java
index 6667c2f..dae922e 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java
@@ -74,7 +74,7 @@
 	}
 
 	boolean contains(DfsStreamKey want, long pos) {
-		return stream == want && start <= pos && pos < end;
+		return stream.equals(want) && start <= pos && pos < end;
 	}
 
 	int copy(long pos, byte[] dstbuf, int dstoff, int cnt) {