Shared multitask prerequisite intermittently executed multiple times

Given a Rakefile

multitask :default => [:a, :b, :c, :d, :e]

task :a => ['target']
task :b => ['target']
task :c => ['target']
task :d => ['target']
task :e => ['target']

rule(/^target$/ => [ 'source' ]) do |t|
    p "#{t.name} => #{t.source}"
    p t.actions
end

file 'source'

the target may get executed multiple times like this

$ ruby --version
ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux-musl]
$ rake --version
rake, version 12.3.1
$ rake --trace --rules
** Invoke default (first_time)
** Invoke a (first_time)
Attempting Rule target => source
** Invoke b (first_time)
Attempting Rule target => source
** Invoke c (first_time)
Attempting Rule target => source
** Invoke d (first_time)
Attempting Rule target => source
(target => source ... EXIST)
** Invoke e (first_time)
Attempting Rule target => source
(target => source ... EXIST)
(target => source ... EXIST)
** Invoke target (first_time)
(target => source ... EXIST)
** Invoke source (first_time)
(target => source ... EXIST)
** Execute source
** Execute target
"target => source"
[#<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>]
"target => source"
[#<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>]
"target => source"
[#<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>]
"target => source"
[#<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>]
"target => source"
[#<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>, #<Proc:0x000055e092b971c0@/repo/Rakefile:10>]
** Execute d
** Invoke target 
** Execute b
** Invoke target 
** Execute a
** Invoke target 
** Execute c
** Invoke target 
** Execute e
** Execute default

The results differ between runs. It seems to happen more often with debug output.

The same action block gets added multiple times to the same task.

Riproduci il problema con il Rakefile fornito usando rake --trace --rules, variando l'output di debug e le esecuzioni ripetute. Traccia gli entry point di multitask e rule-resolution per determinare perché la stessa azione viene aggiunta ripetutamente; il lavoro è completato quando l'azione del target condiviso viene eseguita esattamente una volta in modo coerente.