minor bug on facts entry

["Jorge Vargas" <jorge vargas gmail com>]

Hello guys, I just took a second stab at my "exporter" but this time
I'm using a different approach (code is cleaner), the code is nowhere
near ready but it is currently exporting my database correctly.

Anyway In the process I think I found a bug. For some reason I got
several missing end_time strings. which are read by dbapi as null and
translated to type into None which I'm catching like this

        try:
            fact_duration = fact.end_time-fact.start_time
        except TypeError:
            print "ERROR empty time"
            fact_duration = datetime.timedelta(0)

I got about 3 months worth of data on this particular export and maybe
an averague of 6 entries per day, from all that I got

ERROR empty time
ERROR empty time
ERROR empty time
ERROR empty time
ERROR empty time
ERROR empty time
ERROR empty time
ERROR empty time

so it doesn't seems terrible bad, but it's a bug. I wanted to see if
it's known and or patched.

As for the exporter this time for real I'll have something usable in
the next couple of days, maybe tomorrow if things go right.