Find django spans in the stack

[wiedi]

The django middleware doesn't put the span on the stack directly but instead stores it on the request object. This helps find it anyway.

[codecov]

Codecov Report

Merging #39 (bee1d6a) into master (cc2c2b7) will decrease coverage by 0.78%.
The diff coverage is 62.50%.

@@            Coverage Diff             @@
##           master      #39      +/-   ##
==========================================
- Coverage   98.61%   97.83%   -0.79%     
==========================================
  Files           9        9              
  Lines         362      370       +8     
==========================================
+ Hits          357      362       +5     
- Misses          5        8       +3     

Impacted Files	Coverage Δ
opentracing_utils/span.py	96.05% <62.50%> (-3.95%)	⬇️

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[pitr]

Could this code be added to libs/_django.py instead?

[wiedi]

I am not sure. Do you have a concrete idea what that should look like?

Just placing the span in the stack context instead of attaching it to the request object would probably not be enough since process_view itself won't always be in the stacktrace due to how the django middleware works.