python: please support "gap_handler" keyword argument specified as string

I'm noticing the following regression in the latest version of the python interface top level functions:

jameson.rollins@opslogin0:~ 0$ ipython3 -c "import nds2; nds2.fetch(['H1:GRD-ISC_LOCK_STATE_N'], 1315675378, 1315675379, gap_handler='STATIC_HANDLER_NAN')"
---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-1-3799e1834ed1> in <module>()
----> 1 import nds2; nds2.fetch(['H1:GRD-ISC_LOCK_STATE_N'], 1315675378, 1315675379, gap_handler='STATIC_HANDLER_NAN')

/usr/lib/python3/dist-packages/nds2.py in fetch(channels, gps_start, gps_stop, gap_handler, allow_data_on_tape, hostname, port, protocol, params)
   4057             params.set('GAP_HANDLER', 'STATIC_HANDLER_NEG_INF')
   4058         else:
-> 4059             raise RuntimeError('Invalid gap handler selected')
   4060     if not allow_data_on_tape is None:
   4061         val = 'True'

RuntimeError: Invalid gap handler selected
jameson.rollins@opslogin0:~ 0$ 

This used to work in older minor versions of the 0.16 client.