syscall: terminate error string in exec package on Plan 9 Try to prevent messages like this:         './pack' file does not exist???????????????????????????????????????????????????????????????????????????????????????????????????? TBR=adonovan
syscall: terminate error string in exec package on Plan 9
Try to prevent messages like this:
        './pack' file does not exist????????????????????????????????????????????????????????????????????????????????????????????????????
TBR=adonovan

LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://codereview.appspot.com/66270043

d0f/go-zh,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,bryanxu/go-zh,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,sanjosh/sanjos100-tipc,rdp/rogerpack2005-golang,rdp/rogerpack2005-golang,bryanxu/go-zh,sanjosh/sanjos100-tipc,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,d0f/go-zh,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,d0f/go-zh,bryanxu/go-zh,bryanxu/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,d0f/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,d0f/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,webfd/go-zh,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,rdp/rogerpack2005-golang,rdp/rogerpack2005-golang,rdp/rogerpack2005-golang,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,sanjosh/sanjos100-tipc