Updated ObjectProxy.ensureLocalFile.
Updated ObjectProxy.ensureLocalFile.

mbrukman/gcsfuse,BanzaiMan/gcsfuse,GoogleCloudPlatform/gcsfuse,GoogleCloudPlatform/gcsfuse,GoogleCloudPlatform/gcsfuse,jacobsa/ratelimit,BanzaiMan/gcsfuse,jacobsa/timeutil,kahing/gcsfuse