Merge branch 'js/mingw-isatty'

A hotfix for a topic already in 'master'.

* js/mingw-isatty:
mingw: make stderr unbuffered again

diff --combined compat/winansi.c
index 82b89ab13767a5e562d4f41826d98bce0d704e1c,dac5d01c53e52f75bc6b1d4181fe9cdf9397b2ca..793420f9d0d7732cb7dc2aa94845a22086fe7021
--- 1/compat/winansi.c
--- 2/compat/winansi.c
+++ b/compat/winansi.c
@@@ -510,6 -510,8 +510,8 @@@ static HANDLE swap_osfhnd(int fd, HANDL
         */
        close(new_fd);
  
+       if (fd == 2)
+               setvbuf(stderr, NULL, _IONBF, BUFSIZ);
        fd_is_interactive[fd] |= FD_SWAPPED;
  
        return duplicate;
@@@ -537,7 -539,7 +539,7 @@@ static void detect_msys_tty(int fd
                        buffer, sizeof(buffer) - 2, &result)))
                return;
        name = nameinfo->Name.Buffer;
 -      name[nameinfo->Name.Length] = 0;
 +      name[nameinfo->Name.Length / sizeof(*name)] = 0;
  
        /*
         * Check if this could be a MSYS2 pty pipe ('msys-XXXX-ptyN-XX')
@@@ -547,6 -549,8 +549,8 @@@
                        !wcsstr(name, L"-pty"))
                return;
  
+       if (fd == 2)
+               setvbuf(stderr, NULL, _IONBF, BUFSIZ);
        fd_is_interactive[fd] |= FD_MSYS;
  }