Rename the dummy variable _ to avoid conflict with lazy_gettext

[x4base]

Otherwise "local variable '_' referenced before assignment" will be raised

[landscape-bot]

Repository health increased by 0.14% when pulling 6f3d559 on x4base:underscore_conflict into 88c9516 on airbnb:master.

• 1 new problem was found (including 0 errors and 1 code smell).
• 2 problems were fixed (including 0 errors and 2 code smells).

[coveralls]

Coverage remained the same at 80.869% when pulling 6f3d559 on x4base:underscore_conflict into 88c9516 on airbnb:master.

[mistercrunch]

Hmmm, _ is a common convention for throwaway variables. Can you share the stack trace that prompted this PR?

[x4base]

Surely I know it's a convention, but I won't bother to fix it if it hasn't caused any problem.
It is causing problem because it is used in the same scope as the for loop.
And I chose the name 'unsed' after seeing this comment: http://programmers.stackexchange.com/a/147271

You can decide whether you prefer __, unused, or dummy.

Here is the stack trace.

2016-05-04 09:05:06,285:ERROR:root:local variable '' referenced before assignment
Traceback (most recent call last):
File "/projects/druid/panoramix/caravel/views.py", line 549, in explore
payload = obj.get_json()
File "/projects/druid/panoramix/caravel/viz.py", line 257, in get_json
'data': self.get_data(),
File "/projects/druid/panoramix/caravel/viz.py", line 364, in get_data
df = self.get_df()
File "/projects/druid/panoramix/caravel/viz.py", line 356, in get_df
df = super(TableViz, self).get_df(query_obj)
File "/projects/druid/panoramix/caravel/viz.py", line 143, in get_df
self.results = self.datasource.query(**query_obj)
File "/projects/druid/panoramix/caravel/models.py", line 1196, in query
raise Exception(("No data was returned."))
UnboundLocalError: local variable '_' referenced before assignment
2016-05-04 09:05:06,295:INFO:werkzeug:127.0.0.1 - - [04/May/2016 09:05:06] "GET /caravel/explore/druid/2/?viz_type=table&granularity=one+day&druid_time_origin=&since=7+days+ago&until=now&row_limit=50000&include_search=false&metrics=count&flt_col_0=category_id&flt_op_0=in&flt_eq_0=&slice_id=&slice_name=&collapsed_fieldsets=&action=&datasource_name=live_bi_event&datasource_id=2&datasource_type=druid&previous_viz_type=table&json=true&force=true HTTP/1.1" 500 -
Traceback (most recent call last):
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1836, in call
return self.wsgi_app(environ, start_response)
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1461, in dispatch_request
return self.view_functionsrule.endpoint
File "/Users/clu/.pyenv/versions/druid/lib/python2.7/site-packages/Flask_AppBuilder-1.6.0-py2.7.egg/flask_appbuilder/security/decorators.py", line 26, in wraps
return f(self, _args, *_kwargs)
File "/projects/druid/panoramix/caravel/models.py", line 1254, in wrapper
return f(_args, *kwargs)
File "/projects/druid/panoramix/caravel/views.py", line 553, in explore
raise e
UnboundLocalError: local variable '' referenced before assignment

[x4base]

And coveralls warned about this: https://landscape.io/diff/340487/fixed

[mistercrunch]

Oh I didn't see the scope issue. Merging.