Fix an enc/dec mismatch issue in ext-inter experiment

This commit fixes an encoding decision process issue that could
trigger enc/dec mismatch in the ext-inter experiment.

Change-Id: I6f10d1fd2fd1aa04e51df04c39a65cf72ac66c42
diff --git a/vp10/encoder/rdopt.c b/vp10/encoder/rdopt.c
index c8f5715..ff31e75 100644
--- a/vp10/encoder/rdopt.c
+++ b/vp10/encoder/rdopt.c
@@ -5046,7 +5046,8 @@
         if (!has_second_rf &&
 #if CONFIG_EXT_INTER
             have_newmv_in_inter_mode(this_mode) &&
-            seg_mvs[i][mv_idx][mbmi->ref_frame[0]].as_int == INVALID_MV
+            (seg_mvs[i][mv_idx][mbmi->ref_frame[0]].as_int == INVALID_MV ||
+             vp10_use_mv_hp(&bsi->ref_mv[0]->as_mv) == 0)
 #else
             this_mode == NEWMV &&
             (seg_mvs[i][mbmi->ref_frame[0]].as_int == INVALID_MV ||