[MRG+1] fix: do not catch system exceptions like KeyboardInterrupt

[ankostis]

I noticed that occasionally my Ctrl+C is ignored. In general this happens when using plain except:. In this case, you probably do not want to catch system-exceptions like KeyboardInterrupt.

[Gallaecio]

Thanks!

I’m thinking we should probably use pytest-pylint to detect this kind of issues. I’ll add that to my personal to-do.

[codecov]

Codecov Report

Merging #3726 into master will not change coverage.
The diff coverage is 80%.

@@           Coverage Diff           @@
##           master    #3726   +/-   ##
=======================================
  Coverage   84.89%   84.89%           
=======================================
  Files         168      168           
  Lines        9521     9521           
  Branches     1418     1418           
=======================================
  Hits         8083     8083           
  Misses       1184     1184           
  Partials      254      254

Impacted Files	Coverage Δ
scrapy/contracts/__init__.py	81.3% <0%> (ø)	⬆️
scrapy/utils/misc.py	95.71% <100%> (ø)	⬆️
scrapy/utils/defer.py	96.49% <100%> (ø)	⬆️
scrapy/core/spidermw.py	97.53% <100%> (ø)	⬆️

[codecov]

Codecov Report

Merging #3726 into master will not change coverage.
The diff coverage is 80%.

@@           Coverage Diff           @@
##           master    #3726   +/-   ##
=======================================
  Coverage   84.89%   84.89%           
=======================================
  Files         168      168           
  Lines        9521     9521           
  Branches     1418     1418           
=======================================
  Hits         8083     8083           
  Misses       1184     1184           
  Partials      254      254

Impacted Files	Coverage Δ
scrapy/contracts/__init__.py	81.3% <0%> (ø)	⬆️
scrapy/utils/misc.py	95.71% <100%> (ø)	⬆️
scrapy/utils/defer.py	96.49% <100%> (ø)	⬆️
scrapy/core/spidermw.py	97.53% <100%> (ø)	⬆️

[kmike]

Thanks @ankostis!