[epiphany] Fix leak in ephy_user_agent_get_internal

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 35447e148d69bb5b2349099b3cb1f599c7008f11
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sun Jun 24 16:06:24 2018 -0500

    Fix leak in ephy_user_agent_get_internal
    
    If it returns a nonnull, zero-length string, then we leak it.

 lib/ephy-user-agent.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/lib/ephy-user-agent.c b/lib/ephy-user-agent.c
index 7274db04e..7bcf6f50d 100644
--- a/lib/ephy-user-agent.c
+++ b/lib/ephy-user-agent.c
@@ -35,8 +35,11 @@ ephy_user_agent_get_internal (void)
     return user_agent;
 
   user_agent = g_settings_get_string (EPHY_SETTINGS_WEB, EPHY_PREFS_WEB_USER_AGENT);
-  if (user_agent && user_agent[0])
-    return user_agent;
+  if (user_agent) {
+    if (user_agent[0])
+      return user_agent;
+    g_free (user_agent);
+  }
 
   settings = webkit_settings_new ();
   user_agent = g_strdup_printf ("%s Epiphany/605.1.15", webkit_settings_get_user_agent (settings));