CSV download fails if query tab has atypical characters

[serenajiang]

SQL Lab CSV download fails if the tab name has Chinese characters in it.

Expected results

Successful download

Actual results

INTERNAL SERVER ERROR

Logs:

File "/usr/local/lib/python3.6/dist-packages/gunicorn/http/wsgi.py", line 326, in write
UnicodeEncodeError: 'latin-1' codec can't encode characters in position 223-227: ordinal not in range(256)

How to reproduce the bug

1. Change sqllab tab name to 你好
2. Run an arbitrary query
3. Download csv
4. 😢

Environment

(please complete the following information):

• superset version: up to date with master (last commit a005e4568f14f32be23c317dc484b904ddc71dd9)
• python version: 3.6.8

Checklist

Make sure these boxes are checked before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

[etr2460]

Note that this failure may be specific to implementations where the flask server is run with gunicorn. I'm not sure if this is a Superset bug or a gunicorn bug

[crazyplum]

Same problems discover here.

It seemed to be a superset bug when dealing with header which should be latin-1 encoding.
(May be related to benoitc/gunicorn#1778 )
And a possible solution provided here: #5377

[dpgaspar]

I'm able to reproduce

[stale]

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