Handling exception on cache_key_salt on site update

ee/cli/plugins/site.py

@@ -1307,18 +1307,21 @@ class EESiteUpdateController(CementBaseController):
         if oldcachetype != 'wpredis' and data['wpredis']:
             try:
                 if installwp_plugin(self, 'redis-cache', data):
-                    try:
-                        wpconfig = open("{0}/wp-config.php".format(ee_site_webroot),
-                                  encoding='utf-8', mode='a')
-                        wpconfig.write("\n\ndefine( \'WP_CACHE_KEY_SALT\', \'{0}:\' );"
+                    if EEShellExec.cmd_exec(self, "grep -r \"WP_CACHE_KEY_SALT\" {0}/wp-config.php".format(ee_site_webroot)):
+                        pass
+                    else:
+                        try:
+                            wpconfig = open("{0}/wp-config.php".format(ee_site_webroot),
+                                               encoding='utf-8', mode='a')
+                            wpconfig.write("\n\ndefine( \'WP_CACHE_KEY_SALT\', \'{0}:\' );"
                                      .format(ee_domain))
-                        wpconfig.close()
-                    except IOError as e:
-                        Log.debug(self, str(e))
-                        Log.debug(self, "Editing wp-config.php failed.")
-                        Log.info(self, Log.FAIL + "Editing wp-config failed. "
-                                    "Could not append:"
-                                     " define( 'WP_CACHE_KEY_SALT', '{sitename}:' );")
+                            wpconfig.close()
+                        except IOError as e:
+                            Log.debug(self, str(e))
+                            Log.debug(self, "Editing wp-config.php failed.")
+                            Log.info(self, Log.FAIL + "Editing wp-config failed. "
+                                        "Could not append:"
+                                         " define( 'WP_CACHE_KEY_SALT', '{sitename}:' );")
 
             except SiteError as e:
                 Log.debug(self, str(e))