Fix for complete with side effects

[tkf]

This is found while testing reduce_partition_by.jl.

[codecov]

Codecov Report

Merging #86 (c20e125) into master (0aec3b4) will increase coverage by 0.01%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master      #86      +/-   ##
==========================================
+ Coverage   48.24%   48.26%   +0.01%     
==========================================
  Files           5        5              
  Lines         371      375       +4     
==========================================
+ Hits          179      181       +2     
- Misses        192      194       +2     

Flag	Coverage Δ
Pkg.test-cpu	3.76% <0.00%> (-0.05%)	⬇️
Run.test-cpu	3.76% <0.00%> (-0.05%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/kernels.jl	52.28% <50.00%> (-0.07%)	⬇️

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