goinstall: error out with paths that end with '/'
goinstall: error out with paths that end with '/'

R=adg, rsc, tarmigan+golang
CC=golang-dev
http://codereview.appspot.com/4807048

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

mhennings/marcohennings-go,d0f/go-zh,bryanxu/go-zh,bryanxu/go-zh,Triskite/willstone-goclone,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,sanjosh/sanjos100-tipc,scirelli/scirelli-go,Triskite/willstone-goclone,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,npe9/noahevans-go9,npe9/noahevans-go9,sanjosh/sanjos100-tipc,rdp/rogerpack2005-golang,rdp/rogerpack2005-golang,mhennings/marcohennings-go,Triskite/willstone-goclone,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,npe9/noahevans-go9,scirelli/scirelli-go,Triskite/willstone-goclone,npe9/noahevans-go9,webfd/go-zh,mhennings/marcohennings-go,webfd/go-zh,Triskite/willstone-goclone,glycerine/jeaten-go-arrayof-structof,Triskite/willstone-goclone,glycerine/jeaten-go-arrayof-structof,Triskite/willstone-goclone,d0f/go-zh,bryanxu/go-zh,webfd/go-zh,scirelli/scirelli-go,bryanxu/go-zh,npe9/noahevans-go9,d0f/go-zh,sanjosh/sanjos100-tipc,glycerine/jeaten-go-arrayof-structof,rflanagan/reginaldflanagan-project1,bryanxu/go-zh,webfd/go-zh,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,rflanagan/reginaldflanagan-project1,sanjosh/sanjos100-tipc,d0f/go-zh,bryanxu/go-zh,rflanagan/reginaldflanagan-project1,rdp/rogerpack2005-golang,scirelli/scirelli-go,rflanagan/reginaldflanagan-project1,rflanagan/reginaldflanagan-project1,npe9/noahevans-go9,mhennings/marcohennings-go,Triskite/willstone-goclone,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,d0f/go-zh,mhennings/marcohennings-go,mhennings/marcohennings-go,scirelli/scirelli-go,scirelli/scirelli-go,npe9/noahevans-go9,webfd/go-zh,npe9/noahevans-go9,rdp/rogerpack2005-golang,scirelli/scirelli-go,webfd/go-zh,webfd/go-zh,mhennings/marcohennings-go,glycerine/jeaten-go-arrayof-structof,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,webfd/go-zh,rflanagan/reginaldflanagan-project1,sanjosh/sanjos100-tipc,d0f/go-zh,rdp/rogerpack2005-golang,d0f/go-zh,d0f/go-zh