More robust resetting of the shell.

[arp242]

Don't reset it on Windows, and only reset it if /bin/sh is executable (which
should pretty much always be the case, but it's not in POSIX and IIRC POSIX
explicitly advises against relying on it).

This is basically the same method that vim-plug uses.

This improves #967 and should fix #986.

[fatih]

Use go#util#IsWin() here

[fatih]

Maybe this is just easier (I was going to push it now, but you opened first :)):

function! go#util#System(str, ...)
  if go#util#IsWin()
    let l:output = call(s:vim_system, [a:str] + a:000)
    return l:output
  endif

  let l:shell = &shell
  let &shell = '/bin/sh'
  let l:output = call(s:vim_system, [a:str] + a:000)
  let &shell = l:shell
  return l:output
endfunction

[fatih]

I'm not sure why we have this try clause. Why not just :

let l:output = call(s:vim_system, [a:str] + a:000)
let &shell = l:shell
return l:output

[arp242]

Well, in theory there could be systems that don't have /bin/sh... Those systems are probably very rare, but there's nothing wrong with being paranoid and doing an extra check can't hurt ;-)

The try/finally construct is better in case there are errors. Usually functions continue running commands unless the abort keyword is given, so not re-setting the shell back to l:shell should never happen ... But are you sure there are no situations where Vim doesn't stop running the function on errors? Using finally should guarantee this more...

[fatih]

But are you sure there are no situations where Vim doesn't stop running the function on errors? Using finally should guarantee this more...

So you mean call() might return an error , and in that case we're not able to set the shell back?

[arp242]

But are you sure there are no situations where Vim doesn't stop running the function on errors? Using finally should guarantee this more...

So you mean call() might return an error , and in that case we're not able to set the shell back?

Well, more like the system() function, but yeah.

Like I said, I'm not sure if this really makes a difference... Both versions are probably fine.

[fatih]

Thanks @Carpetsmoker