[gnome-control-center/gnome-3-22] info: Do not crash if Renderer is not set by SessionManager

[Michael Biebl <mbiebl src gnome org>]

commit 97e4d87ae8a123d5b1711ddbaba6bc0d3a0a39a8
Author: Ondrej Holy <oholy redhat com>
Date:   Mon Dec 5 10:15:12 2016 +0100

    info: Do not crash if Renderer is not set by SessionManager
    
    This regression has been introduced by commit 52da4da. The
    info panel crashes if prettify_info() returns NULL. This happens
    if Renderer property from SessionManager is empty.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=774240

 panels/info/info-cleanup.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/panels/info/info-cleanup.c b/panels/info/info-cleanup.c
index 20243ec..bb47493 100644
--- a/panels/info/info-cleanup.c
+++ b/panels/info/info-cleanup.c
@@ -99,6 +99,9 @@ remove_duplicate_whitespace (const char *old)
   GRegex *re;
   GError *error;
 
+  if (old == NULL)
+    return NULL;
+
   error = NULL;
   re = g_regex_new ("[ \t\n\r]+", G_REGEX_MULTILINE, 0, &error);
   if (re == NULL)