Fix latest runtime failure with Racket

[quantum5]

No description provided.

[codecov-commenter]

Codecov Report

Merging #977 (ccf6b5f) into master (79692ed) will increase coverage by 2.71%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #977      +/-   ##
==========================================
+ Coverage   80.63%   83.34%   +2.71%     
==========================================
  Files         138      138              
  Lines        4694     4726      +32     
==========================================
+ Hits         3785     3939     +154     
+ Misses        909      787     -122     

Impacted Files	Coverage Δ
dmoj/cptbox/filesystem_policies.py	98.79% <100.00%> (+0.01%)	⬆️
dmoj/executors/RKT.py	89.28% <100.00%> (ø)
dmoj/judge.py	52.83% <0.00%> (+1.25%)	⬆️
dmoj/executors/java_executor.py	85.35% <0.00%> (+2.02%)	⬆️
dmoj/executors/compiled_executor.py	77.71% <0.00%> (+4.57%)	⬆️
dmoj/utils/communicate.py	93.42% <0.00%> (+5.26%)	⬆️
dmoj/cptbox/tracer.py	77.33% <0.00%> (+18.34%)	⬆️
dmoj/cptbox/handlers.py	100.00% <0.00%> (+25.00%)	⬆️
dmoj/cptbox/isolate.py	73.33% <0.00%> (+36.35%)	⬆️
dmoj/control.py	100.00% <0.00%> (+64.70%)	⬆️

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