Fix check for fence merge success

Change-Id: I9b16526ebfe4ffabf7c4372cca9b192ce046aa21
diff --git a/libs/gui/SurfaceTexture.cpp b/libs/gui/SurfaceTexture.cpp
index 9c76e6e..ed6b73e 100644
--- a/libs/gui/SurfaceTexture.cpp
+++ b/libs/gui/SurfaceTexture.cpp
@@ -338,14 +338,14 @@
         sp<Fence> mergedFence = Fence::merge(
                 String8("SurfaceTexture merged release"),
                 mEGLSlots[mCurrentTexture].mReleaseFence, fence);
-        if (mergedFence.get()) {
+        if (!mergedFence.get()) {
             ALOGE("failed to merge release fences");
             // synchronization is broken, the best we can do is hope fences
             // signal in order so the new fence will act like a union
             mEGLSlots[mCurrentTexture].mReleaseFence = fence;
-        } else {
-            mEGLSlots[mCurrentTexture].mReleaseFence = mergedFence;
+            return;
         }
+        mEGLSlots[mCurrentTexture].mReleaseFence = mergedFence;
     }
 }