vidjil-all-slaves cassé

Plusieurs tests ne passent pas (suite à !412 (merged) ?), au moins sur freebsd.

15:58:01 should-get-tests/vidjil-warning-A.should-get
15:58:01 [1m[31mfailed[0m (0/1) - Warning in json output
15:58:01 [1m[31mfailed[0m (1) - Exit code is 0
15:58:01 [1m[35mcd should-get-tests ;  ../../..//vidjil-algo   -A -g ../../..//germline/homo-sapiens.g:IGH ../data//toy_V.fa ; cat out/toy_V.vidjil | python ../../..//tools/format_json.py -1[0m
15:58:01   stdout --> 74 lines
15:58:01   stderr --> 10 lines
15:58:01 [1m[36mTraceback (most recent call last):
15:58:01   File "../../..//tools/format_json.py", line 15, in <module>
15:58:01     print(json.dumps(json.loads(json_data),
15:58:01   File "/usr/local/lib/python2.7/json/__init__.py", line 339, in loads
15:58:01     return _default_decoder.decode(s)
15:58:01   File "/usr/local/lib/python2.7/json/decoder.py", line 364, in decode
15:58:05     obj, end = self.raw_decode(s, idx=_w(s, 0).end())
15:58:05   File "/usr/local/lib/python2.7/json/decoder.py", line 380, in raw_decode
15:58:05     obj, end = self.scan_once(s, idx)
15:58:05 ValueError: Expecting object: line 1 column 1 (char 0)
15:58:05 [0m
15:58:05 ----------------------------------------