Call to undefined function set_status_header()

[eluser]jzmwebdevelopement[/eluser]
I have a client using CI 1.7.0 and I have the following error can anyone provide any light to this?

Code:

Call to undefined function set_status_header() in /system/libraries/Exceptions.php on line 118

The line is

Code:

set_status_header($status_code);