win32: fix return value of isatty()

Changes to the ls applet upstream assumed that the return value of
isatty() followed the C standard and would be 0 or 1.  The wrapper
for Windows' _isatty() didn't allow for it returning a non-zero
value for a tty, not 1.  This confused ls.

Fix the wrapper.

(GitHub issue #513)

1 files changed, 1 insertions, 1 deletions

diff --git a/win32/winansi.c b/win32/winansi.c
index 9736f0568..427c71f11 100644
--- a/win32/winansi.c
+++ b/win32/winansi.c
@@ -1182,7 +1182,7 @@ char *winansi_fgets(char *s, int size, FILE *stream)
 /* Ensure that isatty(fd) returns 0 for the NUL device */
 int mingw_isatty(int fd)
 {
-        int result = _isatty(fd);
+        int result = _isatty(fd) != 0;
 
         if (result) {
                 HANDLE handle = (HANDLE) _get_osfhandle(fd);