This is highly configurable periodic build scheduler, which triggers
a build at particular times of day, week, month, or year. The
configuration syntax is very similar to the well-known crontab
format, in which you provide values for minute, hour, day, and month
(some of which can be wildcards), and a build is triggered whenever
the current time matches the given constraints. This can run a build
every night, every morning, every weekend, alternate Thursdays,
on your boss's birthday, etc.
   
Pass some subset of minute, hour, dayOfMonth,
month, and dayOfWeek; each may be a single number or
a list of valid values. The builds will be triggered whenever the
current time matches these values. Wildcards are represented by a
'*' string. All fields default to a wildcard except 'minute', so
with no fields this defaults to a build every hour, on the hour. 
The full list of parameters is:
     
name
builderNames
properties
branchminutehourmonthdayOfWeekonlyIfChangedFor example, the following master.cfg clause will cause a build to be started every night at 3:00am:
     from buildbot.schedulers import timed
     s = timed.Nightly(name='nightly',
             builderNames=['builder1', 'builder2'],
             hour=3,
             minute=0)
   This scheduler will perform a build each monday morning at 6:23am and again at 8:23am, but only if someone has committed code in the interim:
     s = timed.Nightly(name='BeforeWork',
              builderNames=['builder1'],
              dayOfWeek=0,
              hour=[6,8],
              minute=23,
              onlyIfChanged=True)
   The following runs a build every two hours, using Python's range
function:
     s = timed.Nightly(name='every2hours',
             builderNames=['builder1'],
             hour=range(0, 24, 2))
   Finally, this example will run only on December 24th:
     s = timed.Nightly(name='SleighPreflightCheck',
             builderNames=['flying_circuits', 'radar'],
             month=12,
             dayOfMonth=24,
             hour=12,
             minute=0)