tests/plugin/callbacks/exception: ensure we have a column number

Author: davidmalcolm

tests/plugin/callbacks/exception/input.c

@@ -17,3 +17,4 @@
    <http://www.gnu.org/licenses/>.
 */
 
+int nonempty;

tests/plugin/callbacks/exception/stderr.txt

@@ -1,4 +1,4 @@
-tests/plugin/callbacks/exception/input.c:1:nn: error: Unhandled Python exception raised within callback
+tests/plugin/callbacks/exception/input.c:20:nn: error: Unhandled Python exception raised within callback
 Traceback (most recent call last):
   File "tests/plugin/callbacks/exception/script.py", line 22, in my_callback
     raise RuntimeError("This is a test of raising an exception")