Decret_2015_1610 can't use len() on generator

[laurentg]

gtfsrun test.sqlite Decret_2015_1610
Traceback (most recent call last):
  File "/usr/local/bin/gtfsrun", line 9, in <module>
    load_entry_point('gtfslib==0.1.0', 'console_scripts', 'gtfsrun')()
  File "/home/g/gtfslib/gtfslib-python/gtfsplugins/gtfsrun.py", line 96, in main
    retval = plugin.run(context, **kwargs)
  File "/home/g/gtfslib/gtfslib-python/gtfsplugins/decret_2015_1610.py", line 111, in run
    urbain = decret_2015_1610(trips)
  File "/home/g/gtfslib/gtfslib-python/gtfsplugins/decret_2015_1610.py", line 26, in decret_2015_1610
    if len(trips) == 0:
TypeError: object of type 'generator' has no len()