We assume these messages are longer than the loop condition accounts for
on the lines following this patch.

  File "/home/pbarker/.local/lib/python2.7/site-packages/pymavlink-2.4.3-py2.7-linux-x86_64.egg/pymavlink/mavutil.py", line 1417, in __init__
    self.init_arrays(progress_callback)
  File "/home/pbarker/.local/lib/python2.7/site-packages/pymavlink-2.4.3-py2.7-linux-x86_64.egg/pymavlink/mavutil.py", line 1463, in init_arrays
    mtype = u_ord(self.data_map[ofs+15]) | (u_ord(self.data_map[ofs+16])<<8) | (u_ord(self.data_map[ofs+17])<<16)
IndexError: mmap index out of range