I realized this was worth doing while working on https://github.com/scrapy/scrapy/pull/5528, but I thought it best not to make it part of that pull request.

I consider it a (minor) bug that we did not check this before, so I am not completely against adding this to 2.6, but since this is not a regression, I also do not see a reason to add this before 2.7.

Codecov Report

Merging #5529 (26f3438) into master (22a59d0) will increase coverage by 0.01%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5529      +/-   ##
==========================================
+ Coverage   88.69%   88.70%   +0.01%     
==========================================
  Files         162      162              
  Lines       10966    10977      +11     
  Branches     1796     1798       +2     
==========================================
+ Hits         9726     9737      +11     
  Misses        960      960              
  Partials      280      280              

Impacted Files	Coverage Δ
scrapy/crawler.py	87.95% <100.00%> (+0.19%)	:arrow_up:
scrapy/utils/reactor.py	79.45% <100.00%> (+2.52%)	:arrow_up: