[gimp] Bug 794023 - Bad/Double free bugs found by scan-build.

[Jehan Pagès <jehanp src gnome org>]

commit 40df83ad71353a28a983900f42f6e19ddddd60f9
Author: Jehan <jehan girinstud io>
Date:   Sat Mar 3 16:25:21 2018 +0100

    Bug 794023 - Bad/Double free bugs found by scan-build.
    
    Thanks to Massimo for raising this issue.

 plug-ins/screenshot/screenshot-gnome-shell.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/plug-ins/screenshot/screenshot-gnome-shell.c b/plug-ins/screenshot/screenshot-gnome-shell.c
index aa6e5da..8a0cb4a 100644
--- a/plug-ins/screenshot/screenshot-gnome-shell.c
+++ b/plug-ins/screenshot/screenshot-gnome-shell.c
@@ -159,6 +159,7 @@ screenshot_gnome_shell_shoot (ScreenshotValues  *shootvals,
     }
 
   g_free (filename);
+  filename = NULL;
 
   retval = g_dbus_proxy_call_sync (proxy, method, args,
                                    G_DBUS_CALL_FLAGS_NONE,