avoid duplcation

Author: IanButterworth

base/stream.jl

@@ -1263,14 +1263,8 @@ end
 function (f::RedirectStdStream)(::DevNull)
     nulldev = @static Sys.iswindows() ? "NUL" : "/dev/null"
     handle = open(nulldev, write=f.writable)
-    _redirect_io_libc(handle, f.unix_fd)
-    c_sym = f.unix_fd == 0 ? cglobal(:jl_uv_stdin, Ptr{Cvoid}) :
-            f.unix_fd == 1 ? cglobal(:jl_uv_stdout, Ptr{Cvoid}) :
-            f.unix_fd == 2 ? cglobal(:jl_uv_stderr, Ptr{Cvoid}) :
-            C_NULL
-    c_sym == C_NULL || unsafe_store!(c_sym, handle.handle)
+    f(handle)
     close(handle) # handle has been dup'ed in _redirect_io_libc
-    _redirect_io_global(devnull, f.unix_fd)
     return devnull
 end
 function (f::RedirectStdStream)(io::AbstractPipe)