bpo-39803: Remove unused str from _PyLong_FormatAdvancedWriter

[petdance]

_PyLong_FormatAdvancedWriter has a PyObject *str that is never used. Remove it.

https://bugs.python.org/issue39803

[codecov]

Codecov Report

Merging #18709 into master will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #18709      +/-   ##
==========================================
- Coverage   82.13%   82.13%   -0.01%     
==========================================
  Files        1956     1955       -1     
  Lines      589972   584600    -5372     
  Branches    44484    44484              
==========================================
- Hits       484584   480157    -4427     
+ Misses      95737    94795     -942     
+ Partials     9651     9648       -3     

Impacted Files	Coverage Δ
Modules/_decimal/libmpdec/fnt.c	0.00% <0.00%> (-83.34%)	⬇️
Lib/distutils/tests/test_bdist_rpm.py	30.00% <0.00%> (-65.00%)	⬇️
Lib/distutils/command/bdist_rpm.py	7.63% <0.00%> (-56.88%)	⬇️
Modules/_decimal/libmpdec/umodarith.h	80.76% <0.00%> (-19.24%)	⬇️
Lib/test/test_urllib2net.py	76.92% <0.00%> (-13.85%)	⬇️
Lib/test/test_smtpnet.py	78.57% <0.00%> (-7.15%)	⬇️
Lib/ftplib.py	63.85% <0.00%> (-6.06%)	⬇️
Lib/test/test_ftplib.py	87.11% <0.00%> (-4.72%)	⬇️
Modules/_decimal/libmpdec/convolute.c	37.14% <0.00%> (-4.29%)	⬇️
Tools/scripts/db2pickle.py	17.82% <0.00%> (-3.97%)	⬇️
... and 330 more

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[shihai1991]

Good Catch.

victor added this var in 2012, so cc @vstinner

[miss-islington]

Thanks @petdance for the PR, and @benjaminp for merging it 🌮🎉.. I'm working now to backport this PR to: 3.8.
🐍🍒⛏🤖

[miss-islington]

I'm having trouble backporting to 3.8. Reason: 'Error 110 while writing to socket. Connection timed out.'. Please retry by removing and re-adding the needs backport to 3.8 label.