[vte] pty: More correct assertion

[Christian Persch <chpe src gnome org>]

commit 3291b8700e77c0254347b0d65cf4ea9595b96199
Author: Christian Persch <chpe gnome org>
Date:   Tue Mar 24 14:58:29 2015 +0100

    pty: More correct assertion
    
    Unlikely this is a problem, but was pointed out in
    https://bugzilla.gnome.org/show_bug.cgi?id=746667

 src/pty.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/pty.c b/src/pty.c
index 1b6966d..7df3907 100644
--- a/src/pty.c
+++ b/src/pty.c
@@ -1338,7 +1338,7 @@ vte_pty_set_utf8(VtePty *pty,
         g_return_val_if_fail(VTE_IS_PTY(pty), FALSE);
 
         priv = pty->priv;
-        g_return_val_if_fail (priv->pty_fd > 0, FALSE);
+        g_return_val_if_fail (priv->pty_fd != -1, FALSE);
 
         if (tcgetattr(priv->pty_fd, &tio) == -1) {
                 int errsv = errno;