You're right it looks just as good in both ways, I should remove the datefmt.
This is whit parameter datefmt.
~~~
./pulse.py config/staging/daily.json 
10 Mar 2014 11:20:39 INFO:automation:Connecting to Mozilla Pulse as "qa-auto@mozilla.com|mozmill_daily|P5139"...
~~~
This is without a datefmt:
~~~
./pulse.py config/staging/daily.json 
2014-03-10 11:23:17,645 INFO:automation:Connecting to Mozilla Pulse as "qa-auto@mozilla.com|mozmill_daily|P5139"...
~~~