Log traceback if exceptions are ignored

[tmarice]

Fixes #611

[WisdomPill]

maybe a nice message? when you use exception you do not need to provide the exception but just a message, thew exception is printed afterwards

[codecov]

Codecov Report

Merging #613 (8a54fa5) into master (44aff88) will increase coverage by 25.6%.
The diff coverage is 0.0%.

❗ Current head 8a54fa5 differs from pull request most recent head 52fc78d. Consider uploading reports for the commit 52fc78d to get more accurate results

@@            Coverage Diff            @@
##           master    #613      +/-   ##
=========================================
+ Coverage    57.8%   83.3%   +25.6%     
=========================================
  Files          39      21      -18     
  Lines        2497    1043    -1454     
  Branches       71       0      -71     
=========================================
- Hits         1441     868     -573     
+ Misses       1041     175     -866     
+ Partials       15       0      -15     

Flag	Coverage Δ
mypy	?
tests	83.3% <0.0%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
django_redis/cache.py	99.2% <0.0%> (+2.3%)	⬆️
django_redis/compressors/lzma.py	0.0% <0.0%> (-93.3%)	⬇️
django_redis/exceptions.py	66.7% <0.0%> (-33.3%)	⬇️
django_redis/compressors/base.py	71.5% <0.0%> (-28.5%)	⬇️
django_redis/hash_ring.py	72.1% <0.0%> (-27.9%)	⬇️
django_redis/serializers/base.py	75.0% <0.0%> (-25.0%)	⬇️
django_redis/__init__.py	30.0% <0.0%> (-10.0%)	⬇️
django_redis/client/default.py	88.8% <0.0%> (-1.5%)	⬇️
django_redis/serializers/pickle.py	100.0% <0.0%> (ø)
tests/test_session.py
... and 22 more

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[tmarice]

@WisdomPill codecov is complaining that the patch isn't covered with tests, so I'll add some that verify that the full traceback was logged.

I'm not sure the mypy failure is related to this PR, though.

[tmarice]

@WisdomPill Do you mind taking another look at the PR?

[WisdomPill]

sorry for being late, and very much thank you for the contribution