[gdm] Don't double-free TryExec variable

[Ray Strode <halfline src gnome org>]

commit 6b28faeac82d3310c3c142187069d10b513cbf97
Author: Ray Strode <rstrode redhat com>
Date:   Wed Jan 20 14:02:15 2010 -0500

    Don't double-free TryExec variable
    
    If the program could not be found the exec variable would get
    freed twice.

 daemon/gdm-session-direct.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/daemon/gdm-session-direct.c b/daemon/gdm-session-direct.c
index d2e1a83..203261b 100644
--- a/daemon/gdm-session-direct.c
+++ b/daemon/gdm-session-direct.c
@@ -540,6 +540,7 @@ get_session_command_for_file (const char *file,
         if (exec != NULL) {
                 res = is_prog_in_path (exec);
                 g_free (exec);
+                exec = NULL;
 
                 if (! res) {
                         g_debug ("GdmSessionDirect: Command not found: %s",