fix race condition error
fix race condition error

When the worker exited the tempfile is not available anymore so we can't
get the last update and calculate the dynamic timeout introduced in
d76bab4d716fed3f965fbde4ba1a1bba975f03d1 .

This changes fix it by catching the IO error.

fix #863

tempbottle/gunicorn,prezi/gunicorn,ephes/gunicorn,keakon/gunicorn,tejasmanohar/gunicorn,jamesblunt/gunicorn,malept/gunicorn,1stvamp/gunicorn,beni55/gunicorn,gtrdotmcs/gunicorn,mvaled/gunicorn,1stvamp/gunicorn,prezi/gunicorn,jamesblunt/gunicorn,z-fork/gunicorn,harrisonfeng/gunicorn,zhoucen/gunicorn,gtrdotmcs/gunicorn,GitHublong/gunicorn,1stvamp/gunicorn,malept/gunicorn,ccl0326/gunicorn,ccl0326/gunicorn,elelianghh/gunicorn,gtrdotmcs/gunicorn,ccl0326/gunicorn,jamesblunt/gunicorn,zhoucen/gunicorn,WSDC-NITWarangal/gunicorn,malept/gunicorn,zhoucen/gunicorn,prezi/gunicorn,mvaled/gunicorn,mvaled/gunicorn,MrKiven/gunicorn