Bug in trying to plot an empty flag

[KarelLigo]

in LLO, on my directory: /home/karelle.siellez/public_html/O1/test/veto_definer_file_VET/test2
Then I run

gwvet-vdf https://code.pycbc.phy.syr.edu/detchar/veto-definitions/download/master/burst/O1/H1L1-HOFT_C01_O1_BURST.xml 1126051217 1127271617

It produces the .sh file, and when I execute it by

./gwpy-vet.sh ```
It gives me a warning that seems to be linked with an attempt to try to analyse/plot a flag with no segments in it. Could you have a look into it please ? 

```/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/matplotlib/patches.py:107: UserWarning: Setting the 'color' property will overridethe edgecolor or facecolor properties. 
  warnings.warn("Setting the 'color' property will override"
/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/matplotlib/patches.py:107: UserWarning: Setting the 'color' property will overridethe edgecolor or facecolor properties. 
  warnings.warn("Setting the 'color' property will override"
/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/matplotlib/__init__.py:892: UserWarning: axes.color_cycle is deprecated and replaced with axes.prop_cycle; please use the latter.
  warnings.warn(self.msg_depr % (key, alt_key))
Traceback (most recent call last):
  File "/home/duncan.macleod/opt/gwpysoft-2.7/bin/gw_summary", line 682, in <module>
    datafind_error=opts.on_datafind_error, **cache)
  File "/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/gwsumm/tabs/data.py", line 370, in process
    **stateargs)
  File "/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/gwvet/tabs.py", line 310, in process_state
    minduration=self.minseglength, vetotag=str(state))[0]
  File "/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/gwvet/core.py", line 88, in evaluate_flag
    out[metric] = _metric(flag, triggers, after=after)
  File "/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/gwvet/metric/__init__.py", line 203, in __call__
    return Quantity(self.method(*args, **kwargs), unit=self.unit)
  File "<string>", line 2, in loudest_event
  File "/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/gwvet/metric/metrics.py", line 53, in _use_dqflag
    return f(segments, *args, **kwargs)
  File "/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/gwvet/metric/metrics.py", line 227, in loudest_event
    arank = get_table_column(after, column).max()
  File "/usr/lib64/python2.7/site-packages/numpy/core/_methods.py", line 10, in _amax
    out=out, keepdims=keepdims)
ValueError: zero-size array to reduction operation maximum which has no identity
/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/matplotlib/patches.py:107: UserWarning: Setting the 'color' property will overridethe edgecolor or facecolor properties. 
  warnings.warn("Setting the 'color' property will override"
/home/duncan.macleod/opt/gwpysoft-2.7/lib/python2.7/site-packages/matplotlib/__init__.py:892: UserWarning: axes.color_cycle is deprecated and replaced with axes.prop_cycle; please use the latter.
  warnings.warn(self.msg_depr % (key, alt_key))