grind: Fix #26 isolate fatal error: MSpanList_Insert on macOS Sierra.
grind: Fix #26 isolate fatal error: MSpanList_Insert on macOS Sierra.

Use a new isolate build for hash 69b5913d2932a6c71209a5a15ec6fa3af56bb73f (Todd 6/3/2015) with Go 1.7.1.

umbrant/dist_test,umbrant/dist_test,cloudera/dist_test,xiao-chen/dist_test,xiao-chen/dist_test,cloudera/dist_test,cloudera/dist_test,umbrant/dist_test,xiao-chen/dist_test,xiao-chen/dist_test,cloudera/dist_test,umbrant/dist_test