daily-lasso can fail on segment gaps

When gaps are present in analysis segments in a given UTC day, daily-lasso is prone to failure because of datafind:

daily-lasso 2020-05-01 11:22:47 CDT     INFO: Generating summary page
/home/detchar/.conda/envs/ligo-summary-3.7/lib/python3.7/site-packages/gwdatafind/http.py:431: UserWarning: Missing segments: 
[1272308400 ... 1272312000)
  warnings.warn(msg)
Traceback (most recent call last):
  File "./daily-lasso", line 346, in <module>
    frametype='SenseMonitor_hoft_%s' % frametype)
  File "/home/detchar/.conda/envs/ligo-summary-3.7/lib/python3.7/site-packages/gwdetchar/io/datafind.py", line 207, in get_data
    verbose=verbose, **kwargs)
  File "/home/detchar/.conda/envs/ligo-summary-3.7/lib/python3.7/site-packages/gwpy/timeseries/core.py", line 314, in read
    return timeseries_reader(cls, source, *args, **kwargs)
  File "/home/detchar/.conda/envs/ligo-summary-3.7/lib/python3.7/site-packages/gwpy/timeseries/io/core.py", line 50, in read
    return io_read_multi(joiner, cls, source, *args, **kwargs)
  File "/home/detchar/.conda/envs/ligo-summary-3.7/lib/python3.7/site-packages/gwpy/io/mp.py", line 103, in read_multi
    return flatten(out)
  File "/home/detchar/.conda/envs/ligo-summary-3.7/lib/python3.7/site-packages/gwpy/timeseries/io/core.py", line 78, in _join
    list_.join(pad=pad, gap=gap),
  File "/home/detchar/.conda/envs/ligo-summary-3.7/lib/python3.7/site-packages/gwpy/timeseries/core.py", line 1627, in join
    out.append(series, gap=gap, pad=pad)
  File "/home/detchar/.conda/envs/ligo-summary-3.7/lib/python3.7/site-packages/gwpy/types/series.py", line 750, in append
    type(self).__name__, self.xspan, other.xspan))
ValueError: Cannot append discontiguous TimeSeries
    TimeSeries 1 span: [1272240000.0 ... 1272308400.0)
    TimeSeries 2 span: [1272312000.0 ... 1272315600.0)

To visualize the gaps that led to this error, see e.g. this plot from the summary pages.

cc @alexandra.macedo, @joshua-smith