6319 assertion failed in zio_ddt_write: bp->blk_birth == txg
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>

@@ -1131,10 +1131,12 @@
                 if (BP_GET_CHECKSUM(bp) == zp->zp_checksum) {
                         BP_SET_DEDUP(bp, 1);
                         zio->io_pipeline |= ZIO_STAGE_DDT_WRITE;
                         return (ZIO_PIPELINE_CONTINUE);
                 }
+                zio->io_bp_override = NULL;
+                BP_ZERO(bp);
         }
 
         if (!BP_IS_HOLE(bp) && bp->blk_birth == zio->io_txg) {
                 /*
                  * We're rewriting an existing block, which means we're