make exception handling syntax consistent

Update exception handling syntax to use the modern style:
except ExcType as localvar

(Bitbake rev: dbf5f42b06bef81749b13aa99945cc1292a6676d)

Signed-off-by: Scott Garman <scott.a.garman@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/runqueue.py

@@ -1228,7 +1228,7 @@ class RunQueueExecuteTasks(RunQueueExecute):
                 modname, name = sched.rsplit(".", 1)
                 try:
                     module = __import__(modname, fromlist=(name,))
-                except ImportError, exc:
+                except ImportError as exc:
                     logger.critical("Unable to import scheduler '%s' from '%s': %s" % (name, modname, exc))
                     raise SystemExit(1)
                 else: