Catch and ignore EEXIST error when creating gsutil tracker dir
Catch and ignore EEXIST error when creating gsutil tracker dir

GoogleCloudPlatform/gsutil,craigcitro/gsutil,dtjackson/gsutil,fishjord/gsutil,mattdr/gsutil,BrandonY/gsutil,ttiurani/gsutil,dimfeld/gsutil,GoogleCloudPlatform/gsutil,chriskuehl/gsutil-debian