Prevent double closing when client connection is released before the last data_received() callback.

[asvetlov]

Fix #3031

[codecov-io]

Codecov Report

Merging #3079 into master will decrease coverage by 0.01%.
The diff coverage is 50%.

@@            Coverage Diff            @@
##           master   #3079      +/-   ##
=========================================
- Coverage   98.11%   98.1%   -0.02%     
=========================================
  Files          42      42              
  Lines        7750    7751       +1     
  Branches     1349    1350       +1     
=========================================
  Hits         7604    7604              
  Misses         51      51              
- Partials       95      96       +1

Impacted Files	Coverage Δ
aiohttp/client_proto.py	95.36% <50%> (-0.64%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 36b27f9...dadf259. Read the comment docs.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a [new issue] for related bugs.
If you feel like there's important points made in this discussion, please include those exceprts into that [new issue].
[new issue]: https:/aio-libs/aiohttp/issues/new